Polymeric additive manufacturing and ophthalmic lenses formed thereby

ABSTRACT

Improved methods and apparatus for additive manufacture of an article with surface qualities conducive to use as an optical element, such as a contact lens. The improvements are directed to repeated application of a monomer according to a pattern of energy transmissibility, such as grayscale image. The method includes intermittent pinning of deposited polymerizable mixture and final cure of the deposited polymerizable mixture. A pattern of multiple defined areas may be manufactured, with each area representing an amount of energy transmissibility associated with that area. Each area may have a light value based upon a scale, such as an 8 bit, 16 bit, 32 bit, 64 bit scale or other scale. In some embodiments, each area may refer to a smallest single component of a digital image.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Number63/306,472, filed Feb. 3, 2022, and U.S. Provisional Application Number63/356,583, filed Jun. 29, 2022, the entire disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of improved additivemanufacturing, and in particular, to methods and apparatus for formingan ophthalmic device by repeated application of droplets ofpolymerizable material representative of a mapping of energytransmissibility, and a resultant lens.

BACKGROUND OF THE INVENTION

Traditional additive manufacturing that includes the application ofmaterial being deposited based upon a computer aided design (CAD) modelor other three dimensional (3D) model has been known. In such processes,a 3D model is sliced into layers, with each layer being a cross sectionof the 3D design. Each cross section is deposited in a sequential mannerto form the article. Sacrificial layers and/or portions of layers mayalso be applied in the form of added material that is subsequentlyremoved.

Materials are typically applied via a sintering process whereby a smallamount of material is melted and placed in a position corresponding to aparticular cross section resulting in a fusion deposition process. Suchtechniques include stereolithography and selective laser sintering.

Additive manufacturing can be low cost and provides more flexibility indesign of a manufactured item and a manufacturing run quantity. However,items formed via additive manufacturing often lack a finished qualityobtainable via other manufacturing techniques, and in particular, lacksufficient surface smoothness.

Contact lens manufacturing has evolved over the past several decadesfrom lathe cutting to spin-cast molding to cast molding which remains asthe most cost effective process. Lathing a contact lens typicallyincludes machining of a single button of lens material at a time until adesired shape is reached. Such processes require complex lathingequipment and specialized operator expertise. In addition, they are notefficient for high volume production of contact lenses.

Cast molding is effective for high volume production of contact lenses,however each lens is formed according to an approximate size and shapeand may vary up to ⅛ or ¼ diopter in a same manufacturing run resultingin a varied patient experience. The varied patient experience issometimes referred to as a “good contact day” and a “bad contact lensday.”

Cast molding of an ophthalmic lens is a complicated process involvingmany variables that are difficult to keep within acceptable parameterscausing varied result in a final product. Variables may arise out of oneor more of: depositing a curable mixture of polymerizable monomers in amold cavity, forming the mold cavity via two mold sections, curing themonomer mixture while it is contained in the cavity, disassembling themold assembly and removing the lens. One mold section forms an anteriorlens surface, and the other mold section forms a posterior lens surface.

The cost of cast-molding equipment is extremely high due to the size ofmanufacturing lines involved. In addition, fabrication of opticalquality metal inserts used to cast the lens mold, and subsequentinjection molding of plastic molds requires a significant up frontexpenditure and associated designs are limited by symmetry constraintsof cast molding techniques. Cast molding also results in a large amountof plastic waste product with detrimental associated environmentalimpact and additional cost.

Still further, cast molding requires management of an inventory of ahuge number of SKUs and associated warehouse management, order pickingand shipping logistical problems, all of which add significantenvironmental detriments and cost to a resulting contact lens product.In addition, a family of contact lenses made by a lens molding processcan only have a limited number of variations such as optical power, basecurve, and diameter.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides improved methods andapparatus for manufacture of an article with surface qualities conduciveto use as an optical element, such as, for example, for use as a contactlens. The improvements presented herein are directed to processesinvolving repeated application of a monomer according to an energyintensity map, such as a grayscale image mapping the intensity of theenergy spectrum associated with visible light. The improved methodsinclude intermittent pinning and final cure of the applied monomer,result result in decreased cost of manufacture, with increasedflexibility of design of a hydrogel based ophthalmic device, includingan ophthalmic device that is not rotationally symmetrical. According tothe present invention, a print head may be placed in a position duringdeposition that is not perpendicular to an apex of the receivingsurface, and droplets may be non-spherical when they contact a receivingsurface. Improvements also include reduction of waste material,decreased environmental impact, decreased warehousing overhead, anddecreased labor required for the manufacture and storing of ophthalmiclenses.

The present invention provides that a lens may be generated via two ormore components, including: an optical zone (sometimes referred toherein as an “OZ”), and a peripheral zone, or edge portion. One or bothof: the optical zone, and the peripheral zone may be formed based uponan energy intensity pattern descriptive of an un-hydrated axialthickness profile.

In some embodiments, additive manufacturing equipment may be controlledto make multiple passes of a print head adding polymerizable materialsto a receiving surface to form a lens (or other article) according to anaxial thickness profile, including an in-air lens power (P), lens indexof refraction (n), center thickness (CT), and back surface radius ofcurvature (RB).

Some embodiments of the present disclosure may include a method offorming an ophthalmic lens via additive manufacturing, the methodincluding the steps of positioning a substrate at a first positionrelative to an additive manufacturing print head and emitting a patternof deposited droplets of polymerizable mixture from the print head, thepattern of deposited droplets of polymerizable mixture correspondingwith a portion of an energy transmissibility map of an ophthalmic lensbeing formed.

Some variants include receiving deposited droplets of polymerizablemixture on a receiving surface, the receiving surface including one orboth of: the substrate, and previously emitted polymerizable mixture.Embodiments may include repositioning the substrate from a firstposition to a next position (current position plus N) relative to aprint head. Repositioning may be accomplished via movement of one orboth of a substrate and a printhead.

Additionally, variants of the present invention include emitting a nextpattern of deposited droplets of polymerizable mixture (first positionplus N) corresponding with a next portion of the energy transmissibilitymap of the ophthalmic lens being formed. Multiple emissions may occurduring a pass of the print head relative to the receiving surface, whichmay include the substrate.

Some variants may include integrating material from the depositeddroplets of polymerizable mixture on the receiving surface and exposingthe integrated material to a pinning process causing partialpolymerization of the deposited droplets of polymerizable mixture.Following a pass of the printhead, one or more of gravity, surfacetension and microforces, may be allowed to act on at least some of thedeposited droplets to smooth a receiving surface, such as levelinginterstitial spaces between deposited droplets.

In some embodiments, at least some of the droplets of polymerizablemixture deposited during a current pass may be integrated withpolymerizable mixture previously deposited onto the receiving surface toform a same volume, which may include a single volume of polymerizablemixture on the substrate. Embodiments may also include pinning depositeddroplets on a receiving surface via partial polymerization of the ofdeposited droplets; and curing the deposited droplets of polymerizablemixture. Integration of deposited droplets alleviates the disclosedprocesses from the requirement of a droplet maintaining a particularshape during deposition, upon impact, or following impact.

In some embodiments, a pinning process may include the step of exposingthe deposited droplets of polymerizable mixture to a first wavelength ofactinic radiation for a limited amount of time sufficient to causegelation of the deposited droplets of polymerizable mixture, yet notcause curing of the deposited droplets.

Additionally, in some embodiments, a cure process may include a step ofexposing deposited droplets of polymerizable mixture to a secondwavelength of actinic radiation for a sufficient time and of sufficientintensity to cause polymerization of deposited droplets of polymerizablemixture deposited in one or multiple cycles of droplet deposition.

The present invention additionally provides for a method of manufacturethat includes a periphery of an object being formed, and a centerportion of the object to be contained with the periphery portion. Forexample, in some embodiments of the present invention, an ocular contactlens with a generally spherical shape may have an edge portion includingan essentially ring shape formed via additive manufacture (or othermanufacturing method, such as machining and/or custom molding) and anoptic zone of the contact lens formed within the perimeter portion viaadditive manufacturing processes. The edge portion is preferably of agreater mass than a center portion that includes an optic zone. Duringformation, a perimeter ring portion may be partially or fully cured, andinternal stresses may be borne more so in heaver mass portions. Formingan edge portion while it is not being acted upon by a center portionallows the edge portion to form with reduced stresses during cure ofdeposited monomer into a polymer. While the examples provided herein aregenerally described with reference to a spherical contact lens, otherembodiments are within the scope of the present invention, such asoblong or crescent shaped contact lenses or other articles, such as acomplex shaped intraocular lens.

In some aspects, the present invention provides for application of apattern of multiple defined areas included within a single lens, witheach area representing an amount of light transmissible through eachrespective associated area. Each area may have a light transmissibilityvalue based upon a scale, such as an 8 bit, 16 bit, 32 bit or 64 bitscale (other scales are also within the scope of the present invention).In some embodiments, each area may refer to a smallest single componentof a digital image. Still further, in some embodiments, a smallestsingle component of the digital image may be referred to herein as a“pixel.” In some embodiments, a pixel may be associated with a distancemeasurement, such as, for example, a quantity of nanometers.

The present invention provides for subsequent application ofpolymerizable material in multiple successive patterns, each successivepattern matching a grayscale image. Following application of eachpattern of the grayscale image, the polymerizable material is pinned,but not fully polymerized.

Following a final application of the monomer in the pattern of thegrayscale image, monomer aggregated from each application of thegrayscale image is polymerized to form a polymer lens, such as, forexample, a hydrogel contact lens formed from etafilcon.

Application of multiple successive grayscale image patterns, which maybe deposited one on top of another, or positioned side by side to eachother, is preferably conducted in a controlled atmosphere. Theatmosphere may be controlled, by way of non-limiting example, to limitspecific amounts of variables, such as one or both of: airborneparticulate and gases present in the atmosphere during specific processsteps involved in a manufacturing process. By way of specific example,preferred embodiments include an atmosphere with a limited an amount ofoxygen to which a monomer is exposed prior to polymerization, and alsolimit a size and an amount of particulate that may interact with themonomer prior to polymerization.

In some embodiments, with some monomers or other polymerizable mixture,oxygen may be controlled as a critical variable involved in free-radicalpolymerization of monomeric materials and prepolymers involved in themanufacturing process. This may be particularly relevant for ophthalmicdevices formed with hydrogels containing relatively low levels ofcross-linker which are to be hydrated after polymerization, and whichare susceptible to easily distort in shape from variations in aresulting polymer network.

According to another aspect of the present invention, exposure ofmonomer or other polymerizable mixture to a gas (such as oxygen) thatmay affect polymerization characterization, is carefully controlled inone or more of: an amount of exposure, a consistency of exposurethroughout the monomer; and a duration of exposure. It has beendiscovered that, during polymerization, if oxygen concentration were tobe higher on one side (Side 1) or other portion of the monomer formingan optical device as compared to a second side (Side 2) or another area,Side 1 may expand relatively more than Side 2, and a distortion ofoptical properties inherent in the optical device formed may occur.Similarly, any portion of a polymerizable mixture with more or lessoxygen concentration may expand in an amount that differs than anotherportion with a different amount of oxygen concentration. By limitingavailability of oxygen to the polymerizable mixture prior topolymerization, a relatively consistent oxygen concentration may bemaintained within the polymerizable mixture, and a consistent swellfactor caused by oxygen concentration is thereby achieved.

In some practices, relatively high concentrations of initiators, highintensity UV light energy, oxygen scavengers, waxes, or coatings may beused to manage the effects of oxygen, prior to polymerization of apolymerizable mixture. However, to date none of these has been shown toconsistently fabricate high quality optical devices.

The present invention takes a novel approach in the use of 3D printingapparatus to create optical elements, such as ophthalmic devices, bycontrolling the presence and concentration of oxygen to low levelsand/or at the same time in adjusted concentrations. In some embodiments,it is beneficial to control a level of oxygen in a polymerizable mixturewith respect to a level of oxygen in an ambient atmosphere of thepolymerizable mixture during manufacture of the optical device in orderto obtain a desired dimensional and resultant optical properties of theoptical element included in the optical device. This principle may alsobe extended to include the substrate on which the deposition printingoccurs. Hence, embodiments include an oxygen level maintained at apredetermined level before and during the polymerization process.

In a first aspect the present invention relates to a method forthree-dimensional deposition printing of an optical element, in whichmethod a plurality of droplets of a polymerizable mixture are depositedonto a surface of a substrate under a controlled atmosphere therebyforming a pattern of energy intensity transmission through the depositedpolymerizable mixture, such as a grayscale with the polymerizablemixture, wherein a controlled atmosphere containing the pattern ofpolymerizable mixture is maintained in a controlled environment with anoxygen concentration of at most about 5.0 volume-% (and preferably atmost about 1.0 volume %), and wherein the oxygen equilibriumconcentration of the polymerizable mixture is at the most about 8.0volume-% (and preferably at most about 2.0 volume %). In this context,due to constraints of measuring a volume % of oxygen in thepolymerizable mixture and ambient environment, “about” may be consideredto be within 10% of the stated amounts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary additive manufacturing apparatus thatmay be used in some implementations of the present invention.

FIG. 2 is a schematic illustration of an alternative 3D printingapparatus according to some embodiments of the present invention.

FIG. 3 illustrates an exemplary energy intensity pattern, represented asa grayscale image, that may be used to generate control protocols for 3Dprinting apparatus according to some embodiments of the presentinvention.

FIG. 4 is a schematic illustration of a spherical lens with anidentified periphery portion according to some embodiments of thepresent invention.

FIG. 5 is a schematic illustration of a profile cutaway view of a lenswith a periphery portion and a carrier portion supporting an optic zone,according to some embodiments of the present invention.

FIG. 6 illustrates a graphical curve representing an exemplary hydratedsurface of an ophthalmic lens that is formable according to the presentinvention.

FIG. 7 illustrates a graphical curve representing an exemplaryunhydrated axial thickness of an ophthalmic lens that is formableaccording to the present invention.

FIG. 8 is a schematic illustration of a false color image of peripheryregion.

FIG. 9 is a schematic illustration of a false color image of the fulllens thickness profile with a transition region zone.

FIG. 10 illustrates a false color image of a thickness profile for aperiphery region zone of an astigmatic lens.

FIG. 11 illustrates a false color image of a thickness profile for anastigmatic lens.

FIG. 12 describes method steps that may be executed while practicingsome implementations of the present invention.

FIGS. 13 and 13A are schematic illustrations of deposited droplets ofpolymerizable mixture integrating into a volume of polymerizable mixturepreviously deposited on a substrate.

FIG. 14 is a schematic illustration of an exemplary change in shape of adroplet of polymerizable mixture after release from a print head.

FIG. 15-15A illustrate a flowchart of method steps that may be executedin some implementations of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for apparatus and methods of applying ofsmall droplets of polymerizable mixture to a surface based upon apattern or map of energy transmissibility. A grayscale image may be usedas a map of transmissibility of visible light energy. A surface may be aplanar surface; an arcuate surface; or a complex variable surface.Droplets of polymerizable mixture applied to the surface accumulate intoa pattern of polymerizable mixture replicating the map of energytransmissibility. Following application of polymerizable mixture to thesurface, the applied polymerizable mixture may be exposed to a limitedamount of actinic conditions, such as radiation (limited in intensityand/duration) and/or thermal energy. Exposure to the limited amount ofactinic radiation is appropriate to pin the applied polymerizablemixture into position.

Polymerizable mixture that has been pinned may act as a subsequentr3eceiving surface and receive additional polymerizable mixture appliedin a pattern of energy transmissibility. After a final application ofpolymerizable mixture, the polymerizable mixture accumulated on thesubstrate surface may be exposed to sufficient actinic conditions, (e.g.radiation and thermal energy) to cure the accumulated polymerizablemixture into a polymer.

An atmosphere encompassing the droplets of polymerizable mixture duringapplication onto the receiving surface and during pendency on thereceiving surface prior to cure, may be carefully controlled in order toachieve a consistent optical quality of a device formed by the curedpolymerizable mixture.

In the disclosure herein, ophthalmic lenses (and/or contact lenses) areused for illustrative and discussion purposes, however the principlesare applicable for the formation of articles of manufacture in generaland the teachings presented may be broadly used in any optical element(or other article) for which precise dimensional shapes; opticalproperties; and/or similar uniform polymer properties are preferred,such as, for example, intraocular lenses.

According to the present invention, in some embodiments, a polymerizablemixture is delivered in the form of extremely small droplets oftypically 1-15 picolitre amounts at high velocities through a gaseousatmosphere with relatively high surface to volume ratios. A large numberof droplets (estimated to be between 1.5 and 9 million) are required toform a 25 milligram lens. In delivering each droplet to a proper placeduring manufacturing, several factors may be considered. The factors mayinclude, but are not limited to, one or more of: exposure of the dropletto ambient process conditions; a thickness of a resulting layer ofmaterial when the droplets impact a surface comprising one or both of asubstrate and previously deposited polymerizable mixture; an interactionwith a receiving surface comprising the substrate and/or previouslydeposited polymerizable mixture, such as wetting of the receivingsubstrate surface and merging with the previously depositedpolymerizable mixture; effects of impinging droplets; pinning via anexposure time to actinic radiation and/or atmospheric gases betweensubsequent layers of droplets of polymerizable mixture; andcuring/polymerization of deposited polymerizable mixture.

During the additive manufacturing process, there is significantopportunity for exposure of the polymerizable mixture to (and uptake of)an ambient gas, such as oxygen, from one or more of: an ambient processatmosphere (sometimes referred to as a controlled atmosphere); areceiving substrate surface; and previously deposited droplets ofpolymerizable mixture; if such factors are not accurately controlled,surface and bulk properties of a resulting ophthalmic lens (includingoptical properties) will be adversely affected.

The influence of oxygen is particularly acute in lenses produced usinghydrogel materials such as 2-hydroxyethyl methacrylate (HEMA) or othermonomers used in soft contact lenses and soft intraocular lenses. Inthese materials, variations caused by exposure to oxygen are moreobvious in a final cured lens after the lens has absorbed water. Inpreferred embodiments therefore, exposure to oxygen may be considered tohave a negative influence.

Typically, surface or skin portions of a lens formed with more oxygenpresent contain more polymer network defects than a bulk portionallowing more water to be absorbed in the areas formed with more oxygenpresent. The resulting distortion in these skin regions usually has anegative impact on the overall mechanical properties (modulus, tensilestrength, elongation), optical properties (light transmission,refractive index etc.), shape, and part to part repeatability.

The present invention teaches control of, and adjusting of an oxygencontent of the polymerizable mixture in relation to the oxygen contentof the controlled atmosphere (as described herein) in order for theeffects of oxygen to be controlled to an extent that the properties ofan optical element formed are not significantly impacted.

In those embodiments that include the formation of ophthalmic devices,(e.g., contact lenses; intraocular lenses; and spectacle lenses), theability to create an optical prescription is highly dependent on preciseshapes of curved surfaces. Producing these required surfaces on theseand other non-ophthalmic optical elements can be achieved by using theprinciples claimed in this invention, thus enabling the benefits ofusing 3D deposition printing such as simplicity, efficiency, moredegrees of freedom in design, lower time requirements, and costs.

In some embodiments, the influence of oxygen in the polymerizationprocess and resulting oxygen impact on properties of an item formed areeliminated or substantially reduced. This enables improved control ofthe movement of the polymerization mixture post deposition during theformation of a polymer matrix in layers. This may be critical in thecreation of curved, arbitrary or irregular surfaces or shapes, and moreso when creating complex optical devices requiring precise curvedsurfaces, including a surface incorporating multiple arcuate portions.Therefore, the combined effects of overcoming oxygen inhibition andcontrolling the movement of the polymerization mixture in opticalproduct applications will likely reduce and even eliminate opticalartifacts and distortions.

In some embodiments, the present invention provides apparatus andmethods of operating the apparatus for three-dimensional depositionmanufacture of an ophthalmic device in which a plurality of droplets ofpolymerizable mixture are deposited onto the surface of a substrate(and/or previously deposited polymerizable mixture) under a controlledatmosphere thereby forming a layer of polymerizable mixture into apattern replicating a map of energy transmissibility (such as agrayscale image).

In some embodiments of the present invention, an oxygen concentration inpolymerizable mixture may be adjusted in relation to one or more of: anoxygen concentration of the controlled atmosphere to which thepolymerizable mixture is exposed; an oxygen concentration in other partsof the environment (such as, for example a substrate receiving dropletsof polymerizable mixture) so that migration of oxygen from one source tothe other is avoided or at least suppressed to a degree that isinsignificant to the polymerization of the polymerizable mixture.

Glossary

In this description and claims directed to the presented invention,various terms may be used for which the following definitions willapply:

“Actinic Radiation” as used herein, refers to emission of energy that iscapable of initiating a chemical reaction in an associated PolymerizableMixture. In some embodiments, actinic radiation includes radiation witha wavelength in a range of 280-450 nm. In some more specific examplesembodiments, an actinic radiation corresponding to UVA and blue lightincludes an energy with a wavelength in the range of 31 5-450 nm, somepreferred embodiments include energy in the 365 nm to 400 nm range.

“Addition Based Manufacture” (sometimes referred to herein as “additivemanufacturing” means a process during which units of material are addedto a structure being formed via the aggregation of the units of materialinto a shape.

“Arcuate” as used herein, refers to a geometric shape including a curvedsurface.

“Cure” as used herein refers to expose a polymerizable mixture toactinic conditions which may include Fixing Radiation and/or thermalenergy of sufficient intensity and for a sufficient duration of time tocrosslink a majority of Polymerizable mixture

“Fixing Radiation” as used herein, refers to Actinic Radiation ofappropriate wavelength, and sufficient intensity and duration tocrosslink a majority of Polymerizable mixture exposed to the FixingRadiation.

“Gelling” or “Gelation” refers to a degree of polymerization sufficientto stop or substantially slow a movement of polymerizable mixturedeposited on a receiving surface while allowing subsequent droplets tomeld with previously deposited polymerizable mixture and form astructure with a single mass of polymerizable mixture withoutdistortion. Gelled polymerizable mixture moves to a higher viscositystate, but stops short of full cure. Pinning or gelation (or gelling)enhances the management of flow and form, and provides a high qualitysurface.

“Gel Point” as used herein shall refer to a point in a polymerizationprocess at which a gel or insoluble fraction is formed. Gel point may beconsidered the extent of conversion at which the liquid polymerizationmixture becomes a high viscous material that is immobile on a stationarysurface. Gel point can be determined, for example, using a Soxhletexperiment: Polymer reaction is stopped at different time points and aresulting polymer is analyzed to determine a weight fraction of residualinsoluble polymer. The data can be extrapolated to a point where no gelis present. This point where no gel is present is the gel point. The gelpoint may also be determined by analyzing a viscosity of a polymerizablemixture during a reaction. The viscosity can be measured using aparallel plate rheometer, with the polymerizable mixture between theplates. At least one plate should be transparent to radiation at thewavelength used for polymerization. The point at which the viscosityapproaches infinity is the gel point Gel point occurs at the same degreeof conversion for a given polymer system and specified reactionconditions.

“Inhibitor” as used herein refers to a chemical reactant or process thatslows or halts a chemical reaction.

“Initiator” as used herein refers to a substance that initiates a chainreaction or polymerization.

“Intensity” as used herein refers to an amount of power transferred perunit area, where the area is measured on a plane perpendicular to adirection of propagation of the energy (e.g., watts per square meter(W/m²)).

“Lens” as used herein “lens” refers to any ophthalmic device thatresides in or on the eye. These devices can provide optical correctionor may be cosmetic. For example, the term lens can refer to a contactlens, intraocular lens, overlay lens, ocular insert, optical insert orother similar device through which vision is corrected or modified, orthrough which eye physiology is cosmetically enhanced (e.g., iris color)without impeding vision.

“Pinning” as used herein refers to the application of actinicconditions, such as exposure to limited actinic radiation, to apolymerizable mixture in an amount sufficient to perform a gelationprocess or gelling, but not cause the polymerizable mixture to cure.

“Polymerizable Mixture” (sometimes referred to as “PM”) as used herein,refers to a liquid mixture of components (reactive and possibly alsonon-reactive components) which upon exposure to an external energy(e.g., actinic radiation in a range of 280-450 nm (e.g., UV-light orblue light or heat) is capable of undergoing polymerization to form apolymer or polymer network. A polymerizable mixture may include amonomer or prepolymer material which can be cured and/or crosslinked toform an ophthalmic lens or modify an existing lens or lens blank.Various embodiments can include Polymerizable mixtures with one or moreadditives such as: UV blockers, bonding agents, tints, photo initiatorsor catalysts, and other additives one might desire in an ophthalmiclenses such as, contact or intraocular lenses. In some embodiments, aPolymerizable mixture may also be a Hydrogel Precursor.

When used herein, the expression oxygen equilibrium concentration of thepolymerizable mixture of X is intended to mean the oxygen concentrationin the polymerizable mixture obtained if the mixture hypothetically isallowed to equilibrate at 1.0 atmospheres (1013 millibar) with anatmosphere having an oxygen concentration of X %.

When used herein, the term optical element is intended to include butnot limited to ophthalmic devices, lenses used in industrialapplications, lenses for endoscopes, inspection devices, fiber opticsdevices, camera lenses, telescopic lenses etc. Currently particularlyinteresting embodiments hereof are ophthalmic devices.

In some embodiments, the optical element has one or more objectsembedded therein, e.g., a solid object selected from inserts,electronics, and functional additive releasing reservoirs or depots.

In other embodiments, the optical element includes one or morefunctionally active substances including biologically active substances.

As used herein an ophthalmic device is any device which is in front ofthe eye or resides in or on the eye or any part of the eye, includingthe cornea, eyelids and ocular glands. These devices can provide opticalcorrection, cosmetic enhancement (e.g. for iris color), visionenhancement, therapeutic benefit (for example as bandage lenses) ordevices which deliver therapeutic agents such as lubricants, wettingagents, active pharmaceutical ingredients (API) and biological agentswhich may be anti-inflammatory, anti-allergy, anti-bacterial,anti-infective, antihypertensive, etc. or delivery of nutraceuticals,vitamins and antioxidants for ocular health or a combination of any ofthe foregoing. Illustrative examples of ophthalmic devices include thoseselected from a spectacle lens, a contact lens (e.g., a soft contactlens or a hard contact lens), an intraocular lens, an overlay lens, acorneal implant, such as a corneal inlay implant, and anophthalmic/ocular insert.

In some embodiments, the ophthalmic device is a contact lens, inparticular a soft contact lens, such as a contact lens of a hydrogelmaterial, other embodiments may include an intraocular lens of hydrogelmaterial.

The term hydrogel refers to crosslinked polymers which have absorbedwater ( swelled) to a water content of at least 10 weight-% thereof.Preferably such hydrogel materials have a water content of at least 20weight-%, such as at least 25 weight-%, and up to 70 to 90 weight-%.

When used herein, the term polymerizable mixture refers to a liquidmixture of components (reactive and possibly also non-reactivecomponents) which upon exposure to an external energy (e.g., actinicradiation 280-450 nm (like UV-light or blue light) or heat) is capableof undergoing polymerization to form a polymer or polymer network.Typically, the mixture comprises reactive components such as monomers,macromers, prepolymers, cross-linkers, and initiators. Moreover, thepolymerizable mixture may further comprise other ingredients likeadditives such as wetting agents, release agents, dyes, light absorbingcompounds such as UV absorbers and photochromic compounds, any of whichmay be reactive or non-reactive but are capable of being retained withinthe resulting ophthalmic device, as well as pharmaceutical, vitamins,antioxidants and nutraceutical compounds. It will be appreciated that awide range of additives may be added based upon the ophthalmic device,which is made, and its intended use.

The fact that the mixture is polymerizable typically implies that one ormore constituents of the mixture (such as, for example, monomer,macromers, prepolymers, cross linkers, etc.) comprise at least onepolymerizable functional group, such as an ethylenically unsaturatedgroup, like it is the case for (meth)acrylate, (meth)acrylamide, vinyl,N-vinyl lactam, N-vinylamide, and styryl functional groups.

In some embodiments, the polymerizable mixture contains at least onehydrophilic component. In some embodiments, the hydrophilic componentscan be selected from the hydrophilic monomers, e.g., those known to beuseful to prepare hydrogels.

In some embodiments, hydrophilic means that at least 5 grams of thecompound(s) are soluble in 100 mL of deionized water at 25° C. underweakly acidic (pH between 5 and 7) or basic conditions (pH form 7 to 9),and in some embodiments 10 grams of the compound(s) are soluble in 100mL of deionized water at 25° C. under weakly acidic or basic conditions.

In contrast to hydrophilic, hydrophobic means that 5 grams ofhydrophobic compound does not fully dissolve in 100 mL of deionizedwater at 25° C. under weakly acidic or basic conditions. The solubilityof the compounds can be confirmed by visual observation, with anyvisible precipitants or turbidity indicating that the compound ishydrophobic. Solubility may be determined after about 8 hours of mixingor stirring.

One class of suitable hydrophilic monomers includes acrylic- orvinyl-containing monomers. Such hydrophilic monomers may themselves beused as crosslinking agents, however, where hydrophilic monomers havingmore than one polymerizable functional group are used, theirconcentration should be limited as discussed above to provide a contactlens having the desired modulus.

The term vinyl-type or vinyl-containing monomers refer to monomerscontaining the vinyl grouping (—CH═CH2) and that are capable ofpolymerizing. Examples of hydrophilic vinyl-containing monomers include,but are not limited to, monomers such as N-vinyl amides, N-vinyl lactams(e.g., N-vinylpyrrolidone ( NVP )), N-vinyl-N-methyl acetamide,N-vinyl-N-ethyl acetamide, and N-vinyl-N-ethyl formamide, N-vinylformamide. Alternative vinyl-containing monomers include, but are notlimited to, l-methyl-3-methylene-2-pyrrolidone,1-methyl-5-methylene-2-pyrrolidone, and5-methyl-3-methylene-2-pyrrolidone.

Acrylic-type or acrylic-containing monomers are those monomerscontaining the acrylic group. (CH2=CRCOX) wherein R is H or CH3, and Xis O or N. which are also known to polymerize readily, such asN,N-dimethyl acrylamide ( DMA ), 2-hydroxyethyl methacrylate ( HEMA ),glycerol methacrylate, 2-hydroxyethyl methacrylamide, polyethyleneglycolmonomethacrylate, methacrylic acid, and mixtures thereof.

Other hydrophilic monomers that can be employed in the inventioninclude, but are not limited to, polyoxyethylene polyols having one ormore of the terminal hydroxyl groups replaced with a functional groupcontaining a polymerizable double bond. Examples include polyethyleneglycol, ethoxylated CI-20 alkyl glucosides, and ethoxylated bisphenol Areacted with one or more molar equivalents of an end-capping group suchas isocyanatoethyl methacrylate, methacrylic anhydride, methacryloylchloride, vinylbenzoyl chloride, or the like, to produce a polyethylenepolyol having one or more terminal polymerizable olefinic groups bondedto the polyethylene polyol through linking moieties such as carbamate orester groups. Other suitable hydrophilic monomers will be apparent toone skilled in the art.

In some embodiments, the hydrophilic component comprises at least onehydrophilic monomer such as DMA, HEMA, glycerol methacrylate,2-hydroxyethyl methacrylamide, NVP, N-vinyl-N-methyl acrylamide,polyethyleneglycol monomethacrylate, and combinations thereof. Inanother embodiment, the hydrophilic monomers comprise at least one ofDMA, HEMA, NVP and N-vinyl-N-methyl acrylamide and mixtures thereof. Inanother embodiment, the hydrophilic monomer comprises DMA and/or HEMA.

The hydrophilic component(s) (e.g., hydrophilic monomer(s)) may bepresent in a wide range of amounts, depending upon the specific balanceof properties desired. In some embodiments, the amount of thehydrophilic component is up to 60 weight-%, such as from 5 to 40weight-% based upon all reactive components.

Hydrophobic silicone-containing components (or silicone components) arethose that contain at least one [—Si—O—Si] group in a monomer, macromeror prepolymer. In some embodiments, the Si and attached O are present inthe silicone-containing component in an amount greater than 20 weightpercent, such as greater than 30 weight percent of the total molecularweight of the silicone-containing component. Useful silicone-containingcomponents include polymerizable functional groups such as acrylate,methacrylate, acrylamide, methacrylamide, N-vinyl lactam, N-vinylamide,and styryl functional groups.

Also, in some embodiments, cross-linking monomers may be employed,either singly or in combination, and may include ethylene glycoldimethacrylate, trimethylolpropane trimethacrylate, glyceroltrimethacrylate, polyethylene glycol dimethacrylate (wherein thepolyethylene glycol has a molecular weight up to, e.g., 400), and otherpolyacrylate and polymethacrylate esters. The cross-linking monomer maybe used in the usual amounts, e.g., from 0.1 to 5, and preferably inamounts of from 0.2 to 3, parts by weight per 100 parts by weight of thepolymerizable mixture.

Another monomer that may also be used is methacrylic acid, which is usedto influence the amount of water that the hydrogel will absorb atequilibrium. Methacrylic acid is usually employed in amounts of from 0.2to 8 parts by weight per 100 parts of the hydrophilic monomers likeHEMA. Other monomers that can be present in the polymerization mixtureinclude methoxyethyl methacrylate, acrylic acid, and the like.

In embodiments, the polymerizable mixture comprises hydroxyethylmethacrylate (HEMA) or hydroxyethyl acrylate (HEA) monomers, preferablyhydroxyethyl methacrylate (HEMA) monomers.

In embodiments, the polymerizable mixture comprises methacrylate oracrylate monomers not being hydroxyethyl methacrylate or hydroxyethylacrylate monomers.

In embodiments, the polymerizable mixture comprises reactive siliconemonomers or oligomers.

In a further embodiment, the polymerizable mixture after polymerizationprovides a polymer which is non-swellable in water, e.g., a polymer thatis not able to take up a water content of more than 2 weight-%.

One or more polymerization initiators may be included in thepolymerizable mixture. Examples of polymerization initiators include,but are not limited to, compounds such as lauryl peroxide, benzoylperoxide, isopropyl percarbonate, azobisisobutyronitrile, and the like,which generate free radicals at moderately elevated temperatures, andphoto-initiator systems such as aromatic alpha-hydroxy ketones,alkoxyoxybenzoins, acetophenones, acylphosphine oxides, bisacylphosphineoxides, and a tertiary amine plus a diketone, mixtures thereof and thelike. Illustrative examples of photo-initiators are 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one,bis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide (DMBAPO),bis(2,4,6-trimethylbenzoyl)-phenyl phosphineoxide (Irgacure 819),2,4,6-trimethylbenzyldiphenyl phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin methyl ester and a combination ofcamphorquinone and ethyl 4-(N,N-dimethylamino)benzoate. Commerciallyavailable ultra-violet and visible light initiator systems include, butare not limited to, Irgacure 819® and Irgacure 1700® (from CibaSpecialty Chemicals) and Lucirin TPO initiator (available from BASF).Commercially available UV photo-initiators include Irgacure 651, Darocur1173 and Darocur 2959 (Ciba Specialty Chemicals). These and otherphoto-initiators which may be used are disclosed in Volume III,Photoinitiators for Free Radical Cationic & Anionic Photopolymerization,2nd Edition by J. V. Crivello & K. Dietliker; edited by G. Bradley; JohnWiley and Sons; New York; 1998.

In some embodiments, a polymerization initiator is included in apolymerizable mixture in amounts capable of initiating polymerization ofthe polymerizable mixture, such as 0.1 to 2 weight-%. Polymerization ofthe polymerizable mixture can be initiated using the appropriate choiceof heat or visible or ultraviolet light, or other energy, depending upona polymerization initiator used. Alternatively, in some embodiments,initiation can be conducted without a photo-initiator using, forexample, e-beam. However, when a photo-initiator is used, the preferredinitiators are bisacylphosphine oxides, such asbis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (Irgacure 819®) or acombination of 1-hydroxycyclohexyl phenyl ketone and DMBAPO, and inanother embodiment the method of polymerization initiation is viavisible light activation.

In some embodiments, a polymerizable mixture may include one or moreinternal wetting agents. Internal wetting agents may include, but arenot limited to, high molecular weight, hydrophilic polymers. Examples ofinternal wetting agents include, but are not limited to, polyamides suchas poly(N-vinyl pyrrolidone) and poly(N-vinyl-N-methyl acetamide).

The internal wetting agent(s) may be present in a wide range of amounts,depending upon the specific parameter desired. In some embodiments, theamount of the wetting agent(s) is up to 50 weight-%, such as from 5 to40 weight-%, such as from 6 to 30 weight% based upon all reactivecomponents.

Moreover, a polymerizable mixture may contain one or more auxiliarycomponents selected from, but not limited to, chelating agents,polymerization inhibitors, viscosity regulating agents, surface tensionregulating agents, glass transition regulating agents, compatibilizingcomponents, ultra-violet absorbing compounds, medicinal agents likeophthalmic pharmaceutical agents, ophthalmic demulcents, excipients,antimicrobial compounds, copolymerizable and non-polymerizable dyes,release agents, reactive tints, pigments, and chelating agents, andcombinations thereof. In some embodiments, the sum of such auxiliarycomponents may be up to 20 weight-%. Preferred embodiments may includephoto initiators that create reactive species when exposed to one ormore of visible light, ultraviolet light, red light, and infrared light,and may include one or more of a: visible light, ultraviolet light, redlight, and infrared light absorbing moiety,

A polymerizable mixture may be prepared, for example, by simple mixingof the constituents of the mixture. In some embodiments, reactivecomponents (e.g., hydrophilic monomers, wetting agents, and/or othercomponents) are mixed together with an inert diluent to form thepolymerizable mixture. Such diluents may have the effect of controllingexpansion of an ophthalmic device formed upon hydration, assisting insolubility of components, and regulating a glass transition temperature.Other embodiments may exclude the inert diluent.

Classes of suitable diluents include, without limitation, alcoholshaving 3 to 20 carbons, amides having 10 to 20 carbon atoms derived fromprimary amines, ethers, polyethers, ketones having 3 to 10 carbon atoms,and carboxylic acids having 8 to 20 carbon atoms. As the number ofcarbons increase, the number of polar moieties may also be increased toprovide the desired level of water miscibility. In some embodiments,primary and tertiary alcohols are preferred. Preferred classes includealcohols having 4 to 20 carbons and carboxyl ic acids having 10 to 20carbon atoms.

In some embodiments, the diluents are selected from 1,2..octanediol,t-amyl alcohol, 3-methyl-3-pentanol, decanoic acid,3,7-dimethyl-3-octanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol,3,3-dimethyl-2-butanol, tripropylene methyl ether (TPME), butoxy ethylacetate, mixtures thereof and the like.

In some embodiments, the diluents are selected from those that have somedegree of solubility in water. In some embodiments at least about threepercent of the diluent is miscible with water. Examples of water solublediluents include, but are not limited to, I-octanol, 1-pentanol,1-hexanol, 2-hexanol, 2-octanol, 3-methyl-3-pentanol, 2-pentanol, t-amylalcohol, tert-butanol, 2-butanol, 1-butanol, ethanol, decanoic acid,octanoic acid, dodecanoic acid, 1-ethoxy-2-propanol,1-tert-butoxy-2-propanol, EH-5 (commercially available from EthoxChemicals), 2,3,6,7-tetrahydroxy-2,3,6,7-tetramethyl octane,9-(1-methylethyl)-2,5,8,10,13,16-hexaoxaheptadecane,3,5,7,9,11,13-hexamethoxy-1-tetradecanol, mixtures thereof and the like.Esters of alcohols such as boric acid esters of alcohols are otherembodiments of diluents.

In some embodiments, an amount of diluent preferred is typically up to60 weight-%, such as from 10 to 60 weight-%, such as from 20 to 50weight-%, based upon the complete polymerizable mixture.

In another aspect, in some embodiments, a polymerizable mixture includesone or more cross-linkers in an amount of 0.5 to 5.0 weight-%, one ormore non-reactive diluents (such as polyhydric alcohols, esters ofpolyhydric alcohols or ethers of polyhydric alcohols, e.g. glycerols andglycerol esters) in an amount of 0 to 60.0 weight-%, and one or morepolymerization inhibitors in an amount of less than 100.0 ppm andpreferably less than 50.0 ppm, based on the weight of the polymerizablemixture. A viscosity of the polymerizable mixture may also play animportant role, and is typically 1-25 cP, such as 2-15 cP, in particular3-10 cP, although other viscosities are within the scope of the presentinvention.

As mentioned above, the oxygen equilibrium concentration of thepolymerizable mixture is preferably 0.05-8.0 volume-%, e.g., 0.2-6.0volume-%, e.g., in the range of 0.5-6 volume-%. The lower limits (suchas 0.05%, 0.1%, 0.2% etc.) are stated for practical reasons and it isquite possible to achieve even lower concentrations.

An oxygen content of a polymerizable mixture may be adjusted to adesired level (X) by exposing the polymerizable mixture (previouslybeing mixed under an ambient atmosphere (1013 mbar, 21 volume-% O2)) toa reduced pressure P, where P=X*1013/21 mbar. Subsequently the reducedpressure (sometimes referred to as a “vacuum”) can be released and theoxygen-adjusted polymerizable mixture can be stored under an atmospherehaving an oxygen concentration corresponding to a suitable atmospherehaving an oxygen concentration of X.

In some preferred embodiments, the oxygen concentration in a controlledatmosphere ambient to deposited polymerizable mixture, and a substratein contact with the polymerizable mixture is lower than the oxygenequilibrium concentration in the polymerizable mixture.

3D-Printing Device

The deposition of a plurality of droplets is typically achieved using anadditive manufacturing printhead. Such printheads are capable ofsimultaneous deposition of a plurality of droplets of a liquid either ina one-dimensional pattern (in the form of lines) or in a two-dimensionalpattern. In some embodiments, a droplet is preferably in a smaller rangefor additive manufacturing, such as, for example, in a picolitre range,such as between about 3 picolitres and 20 picolitres per droplet andpreferably 10 to 30 passes of a printhead in relation to a substrate.

In some embodiments, a desired speed and accuracy of a deposition of theplurality of droplets may be accomplished with an additive manufacturingprinthead capable of simultaneous deposition of a two-dimensionalpattern of polymerizable mixture so that a pattern (or multiplesuccessive patterns) of droplets of the polymerizable mixturerepresenting an integer map of energy transmissibility (e.g., agrayscale image) of the ophthalmic device can be printed.

In some preferred embodiments, such as the embodiments used to form theworking examples disclosed herein, a two-dimensional patternrepresenting an integer map of energy transmissibility in the form of agrayscale image is achievable in a single pass of a printhead depositingdroplets in an area at least the size of the ophthalmic device.Commercially available printing heads suitable for this purpose includethe Samba™ printhead from Fujifilm, e.g., Samba^(Tm)G3L Printhead whichhas 2048 nozzles per module and is capable of deposition of liquids inthe order of 2.4 picolitre for native drop size to 13.2 picolitremaximum drop size at a 1200 native dpi accuracy.

A pattern of each pass of droplets deposited by the 3D-printing device,may be determined in relation to a desired transmissibility pattern ofan optical lens to be formed and a shape of the optical lens beingformed that correlates with the transmissibility pattern. For example(in case of an ophthalmic device), data gathered from measuring apatient’s eye may be used to generate input. Data may include, forexample, optical characteristics, surface properties, size and shapedimensions and observations of an ocular disease state.

Three-dimensional (3D) printable models may be created based upon acomputer aided design (CAD) package or scan of a patient’s eye. Patienteye scanning may include collecting and analyzing digital datarepresentative of the shape and appearance of a patient’s eye. Based oncollected data, a three-dimensional model of a target ophthalmic devicemay be produced. The 3D model may be processed by software to convertthe model into a grayscale image (or other energy intensity mapping) andproduce a file containing instructions tailored to a specific type of 3Dprinter to repeatedly apply polymerizable mixture according to thegrayscale image or other energy transmissibility pattern.

Substrate

The present invention provides for depositing a plurality of droplets ofpolymerizable mixture onto a surface of a substrate. Suitable materialsfor the substrate include one or more of: glass, polyolefins likepolypropylene, polystyrene, and other smooth materials.

In some preferred embodiments, a form of a substrate represents a shapeof one side of a resulting (non-hydrated) ophthalmic device, e.g., itmay include at least a portion that is arcuate or otherwise curved for acontact lens and relatively flat for an intraocular lens. The size ofthe substrate is preferably adjusted to fit a required dimension of afinished hydrated ophthalmic device. The substrate with a rotationalaxis may be formed by one or more of: lathing, grinding, and injectionmolding. A substrate that is not constrained to shapes with a rotationalaxis may be prepared via other processes, such as 3D-printing. Asubstrate may therefore include an optical surface shape that is notspherical, such as a substrate surface shape based upon a portion of apatient’s eye exposed to air.

In some embodiments, in order to adjust wettability of a surface of asubstrate that will receive polymerizable mixture, a surface of thesubstrate may be pre-treated with one or more of: a surfactant; exposedto UV; exposed to ozone; and exposed to plasma treatment; or acombination of these treatments. In some preferred embodiments, areceiving surface of a glass or polymer substrate may be pre-treatedwith Tween 80 or a silicone surfactant such as Dow Coming Additive 67,Additive 14, Additive 57, Xiameter OFX-0193 etc. In some implementationsof the present invention, a surfactant could be included in thepolymerizable mixture.

In some embodiments, a method of manufacture of an ophthalmic lensincludes bringing an oxygen concentration in the substrate intoequilibrium with an oxygen concentration in the controlled atmosphere.Similarly, in some preferred embodiments, an oxygen concentration in thesubstrate is the same or less than an oxygen content of a polymerizablemixture deposited on the substrate.

In order to obtain an oxygen concentration in the substrate which is inequilibrium with the oxygen concentration in the controlled atmosphere,the substrate may simply be allowed to be exposed to the controlledatmosphere (or a corresponding atmosphere) prior to the deposition ofthe droplets, e.g., for a period of at least 8 hours.

In some embodiments, a substrate may only be capable of a limited amountof oxygen within it, hence, it may not be necessary to take anyparticular precautions with respect to the oxygen concentration in thesubstrate.

In an alternative embodiment, the substrate is in itself an ophthalmicdevice (such as, for example, a regular commercial contact lens), thatis modified by the methods described herein so as to form a finalophthalmic device, such as, for example an ophthalmic device modified tohave one or more of′ different optical properties; an ophthalmic devicewith modified color patterns; and an ophthalmic device with differentphysical properties.

Controlled Atmosphere

In some embodiments, an ambient atmosphere in which the depositionprinting described herein takes place may be controlled. A controlledambient atmosphere may include, by way of non-limiting example, one orboth of: defined ranges of a specified gas, defined ranges ofparticulate and controlled wavelengths of light or other energywavelength. In some preferred embodiments, a suitably low concentrationof oxygen is achieved in an atmosphere encompassing the polymerizablemixture such that an oxygen content of the polymerizable mixture isappropriately controlled. In some embodiments, the receiving surface ofthe substrate may be contained within the controlled ambient atmosphere.

By way of specific non-limiting example, in some embodiments, acontrolled atmosphere has an oxygen concentration of at the most 5.0volume-%. In some embodiments, an oxygen concentration in a controlledatmosphere is at most 2.0 volume-%, e.g., 0.01-2.0 volume-%, such as0.03-1.5 volume-%, e.g., in the range of 0.05-1.2 volume-%, such as0.1-1.1 volume-%, and more preferably at the most 1.0 volume-%. Thelower limits (such as 0.01%, 0.03%, 0.05% etc.) are stated for practicalreasons and it is quite possible to achieve even lower concentrations.

In another aspect, in some embodiments, a controlled atmosphere underwhich deposition of a polymerizable mixture takes place is mostconveniently at a pressure of 1.0 atm. (1013 mbar) which corresponds toan oxygen concentration of 21 volume-%. A lower oxygen concentrationthan the 21 volume-% found in a normal atmosphere may suitably beobtained by mixing of atmospheric air with another gas, such as, in somepreferred embodiments, an inert gas such as, one or more of nitrogen,helium, argon, or other inert gas.

In some embodiments, a controlled atmosphere may include an inert gas,such as nitrogen, mixed in specific amounts with pure oxygen. Onepreferred approach for controlled atmosphere uses nitrogen as the inertgas to displace atmospheric oxygen and thereby achieve an oxygenconcentration of a desired level.

An oxygen concentration may be monitored by an oxygen meter andregulated at one or more of: prior to an additive manufacturing process,at a start of an additive manufacturing procedure, and during themanufacturing procedure and preferably also intermittently orcontinuously controlled during a process preparing one or both of: anoptical element and a substrate.

Depositing Additive Droplets and Curing

The methods of the present invention include depositing successivepasses of a plurality of droplets of a polymerizable mixture onto asurface of one or both of a substrate, and previously depositeddroplets, under a controlled atmosphere. The droplets of polymerizablemixture are preferably emitted from a printhead and deposited based upona two dimensional pattern representative of an energy transmissibilitypattern, such as a grayscale image (or other light map representinglight intensity). Following a deposition of droplets of thepolymerizable mixture, the droplets may be exposed to controlled amountsof actinic radiation to cause a gelation process that pins the dropletsof polymerizable mixture in place relative to the substrate.

A polymerizable mixture is typically deposited using a 3D-printingdevice, such as, for example, the printing devices described herein. Inembodiments, individual droplets have a volume of 0.5-50 pL, such as1-40 pL, or 1.5-30 pL, like 2.0-15 pL.

In some embodiments, each plurality of droplets of the polymerizablemixture is deposited onto a surface relative to a substrate. The surfacerelative to the substrate may include the droplets coming into contactwith one or more of: an upper surface of the substrate; dropletspreviously deposited; and an article placed upon one or both of thesubstrate and the previously deposited droplets of polymerizablemixture. Polymerizable mixture that is deposited onto previouslydeposited polymerizable mixture may integrate into previously depositedpolymerizable mixture such that a single mass of polymerizable mixtureforms on the substrate with no discernable layers. After coming intocontact with the surface, the polymerizable mixture may subsequently beexposed to limited actinic radiation or heat after the deposition of thefinal of the successive layers of droplets for forming the ophthalmicdevice. Droplets of polymerizable mixture deposited upon an article mayattach to the article. The article may have a surface treated with awetting agent.

In variations of the present invention where successive dispositionslayers of deposited polymerizable mixture are exposed to actinicradiation (e.g., UV light), the polymerizable mixture may include aphoto-initiator. In the variants of the present invention where thepolymerizable material disposed in successive passes are exposed toheat, the polymerizable mixture may include a thermal initiator.

In some variants of the present invention, successive patterns areexposed to intermittent radiation (e.g., UV light) after each depositionof a layer of droplets. A degree of polymerization obtained by suchintermittent exposure to actinic radiation is typically to that requiredfor the purpose of pinning, or otherwise obtaining gelation of, thepolymerizable mixture so as to control migration of deposited dropletsfrom a first position to another position. In preferred embodiments,such control of migration allows for limited flow of depositedpolymerizable mixture but prevents unmitigated rearranging of thedeposited polymerizable mixture. For example, in some embodiments,controlled migration allows gravity to integrate deposited droplets withpreviously deposited polymerizable mixture, and meld into a smoothedsurface of polymerizable mixture that is then pinned in place with agelation process.

In some embodiments of the present invention, a plurality of droplets ofpolymerizable mixture are deposited onto a surface that includes one orboth of the substrate and previously deposited polymerizable mixture,thereby forming a pattern of polymerizable mixture with energytransmissibility properties based upon an integer map representingenergy transmissibility, such as a two dimensional grayscale image thatis referenced to control the printhead.

Deposited polymerizable mixture is preferably exposed to pinning actinicradiation after each pass (or some passes) of the printhead depositingthe polymerizable mixture, and ultimately exposed to curing actinicradiation after a deposition of a final pass of a printhead depositingdroplets polymerizable mixture to form the optical element.

A pass of the print head may include one or both of: the print headmoving relative to a substrate onto which polymerizable mixture isreceived, a substrate and previously deposited polymerizable mixture)moving relative to a printhead; and/or a printhead and a substratemoving relative to each other as the polymerizable mixture is deposited.In some preferred embodiments, at least some of a pattern ofpolymerizable mixture deposited via a pass subsequent to a first pass ofthe printhead combines with and integrates into previously depositedpolymerizable mixture, thereby forming a single volume polymerizablemixture. Gravity induces a limited movement of the depositedpolymerizable mixture resulting in a smoothing of the surface of thedeposited polymerizable mixture movement based upon gravity may belimited by surface tension forces and micro forces. Preferably thesingle volume of polymerizable mixture is pinned and/or gelled byexposure to a limited amount of actinic radiation thereby limitingadditional movement following the smoothing effect of gravity inducedmovement.

In some variants of the present invention, a series of successive passesof a printhead, such as, for example, between two to twenty (2-20)passes of polymerizable mixture are deposited before exposing thedeposited polymerizable mixture to intermittent actinic radiation thatis effective to pin and/or gel the deposited polymerizable mixture.Prior to exposure to the intermittent actinic radiation, the depositedpolymerizable mixture may undergo limited migration as a single volumeof polymerizable mixture.

In some embodiments, an amount of polymerizable mixture deposited in apass of the printhead in any particular portion of the receiving surfacemay be up to 50 µm, but preferably a maximum of 25 µm.

In some variants of the present invention, a polymerizable mixtureincludes a plurality of photo-initiators, with two or morephotoinitiators having responsiveness to different wavelengths ofactinic radiation. This is particularly interesting when it is desirableto utilize UV light at one wavelength for the intermittent exposure (forpinning or gelation) and another wavelength for final curing ofdeposited polymerizable mixture to form the optical element.Accordingly, in some variants of the present invention, a firstpolymerization initiator is used (in conjunction with exposure to anappropriate first actinic radiation) to create a construct of partiallypolymerized polymerizable mixture, and a second polymerization initiatoris used (in conjunction with exposure to an appropriate second actinicradiation) to complete a curing process.

In addition to controlling a level of oxygen in the polymerizablemixture to within a desired range of oxygen content, some embodiments ofthe present invention include controlling polymerization of thedeposited polymerizable mixture such that as an optical element is beingfabricated using the processes described in this disclosure, a degree ofpolymerization of deposited polymerizable mixture within a specifiedtimeframe following deposition is limited to a degree of gelation tostop, or substantially slow, a movement of the polymerization mixturewhile allowing droplets from subsequent passes to meld into previouslydeposited polymerizable mixture and form a structure for an opticalelement with limited distortion.

A process for intermittent gelation may sometimes be referred to aspinning or gelling of the deposited polymerizable mixture. In somevariants of the present invention, a pinning process may includeapplying a dose of actinic radiation in an intensity, wavelength andlength of time suitable to cause gelation, such as, for example,application of ultraviolet (UV) light to a UV curable polymerizablemixture and/or ink (UV ink). Actinic radiation wavelengths may bematched to photochemical properties of a polymerizable mixture and/or UVink used in a manufacturing process.

As a result of the intermittent gelation, deposited polymerizablemixture and/or ink droplets move to a higher viscosity state, but stopshort of full cure. Variants of the present invention that includepinning or gelation (or gelling) have enhanced ability to manage a flowand form of deposited polymerizable mixture, which in turn provides highoptical qualities in an optical element formed via final cure of thedeposited polymerizable mixture. For example, sufficient flow to allowgravity to smooth a surface of the gelled polymerizable mixture but notsignificantly change a shape of an optical element is preferred. In somevariants, other forces, such as, for example, centrifugal force may beused to form a surface shape.

Processes for gelation and cure may be modified based upon a selectionand/or a concentration of one or more of: photo-initiators,cross-linkers, source of actinic radiation (e.g., UV light source),intensity of actinic radiation and duration of exposure. Examples ofsources of actinic radiation may include light emitting diodes (LED) orlight bulbs, lasers or the like.

In some specific embodiments, two photo-initiators absorbing at twodifferent wavelengths are used with corresponding UV LED light sources(e.g., at 365 nm and at 400 nm). One initiator may be present in aconcentration capable of starting gelation of the polymerizable mixturebut insufficient to complete the polymerization. This enables individuallayers to come to a same relative degree of conversion prior to finalcure. A final polymerization throughout the optical element may be doneas a separate step using another photo-initiator/UV LED lightcombination (e.g.; second photoinitiator’s actinic radiation energy, orthird photoinitiator’s etc.) actinic radiation energy resulting in auniform polymer network required for optical function.

As an alternative hereto, a thermal initiator that is active at or abovea Tg may be used instead of, or in addition to, the second (or other)photo-initiator to complete curing of the deposited polymerizablemixture. The present invention also provides that without control of anoxygen content of deposited polymerizable mixture throughout depositionprocess steps, and during a final curing step, the oxygen inhibitioneffects would adversely impact the uniformity of the polymer network andmay lead to creation of incompletely cured polymer and therefore adevice with a tacky surface.

In some embodiments, a polymerizable mixture is deposited onto a curvedsurface, a first deposition, or multiple depositions, may be depositedas patterns of droplets of polymerizable mixture onto a curved surface,according to the methods described herein. The patterns of dropletsinclude a volume and distribution that permits surface tension tomaintain a patterns of droplets of polymerizable mixture with limitedflow or other movement until partially cured with a gelation processthereby pinning the deposited polymerizable mixture in place.

Subsequent deposition of additional droplets from the print head mayfill in spaces left behind by a first deposition or subsequent layersuntil a surface of a receiving substrate is completely covered and isestablishes as a foundational to build an optical element upon.Alternatives to dot patterns include deposition of droplets to form avery thin layer (e.g., 1 micron to 8 microns) and building an opticalelement upon such very thin layer with the processes disclosed herein.

In some embodiments, it is useful to isolate a print head containingmonomer from receiving actinic radiation, such as UV radiation in orderto prevent premature gelation or polymerization of monomers in a printhead which may render the print head inoperable, or operable atdiminished performance levels. Isolation from actinic radiation isparticularly important when using reactive monomers with low levels ofinhibitors and/or using a print head in an environment with low oxygenlevels.

In order to achieve concurrent printing and pinning of a material tostop or slow the movement of deposited ink or polymerizable mixture oncedeposited, some embodiments of the present invention include apparatusoperative to isolate a source of actinic radiation (e.g., UV lightsource) from the print head to essentially eliminate or substantiallyreduce a potential of gelation/polymerization of polymerizable mixturein the printhead. Isolating the print head from a source of actinicradiation and controlling both oxygen levels and movement ofpolymerization mixture, enables the fabrication of precise shapes andoptical devices without artifacts in the matrix that adversely affect anoptical performance of a final lens that is fabricated.

In some embodiments, it is preferred that to wash gelled depositedpolymerizable mixture with a solvent or water, e.g., to remove excessmonomers, after multiple depositions of polymerizable mixture(s) andgelation processes have been completed, but before a final curingprocess is performed.

Referring now to FIG. 1 , a schematic diagram illustrates an example ofadditive manufacturing systems 100 with the apparatus and underlyingsoftware, which when executed, the software makes the apparatusoperative. As illustrated, the additive manufacturing system 100includes one or more additive manufacturing print devices 101-102 thatare operative to deposit droplets 110 of a polymerizable mixture 103 ina pattern of energy intensity and/or energy transmissibility (e.g., agrayscale pattern) onto a receiving surface 103A supported by asubstrate 104. The receiving portion 104A of the substrate 104 may besmooth and arcuate in a manner making it suitable as a back curve of acontact lens. The receiving surface 103A may include one or both of thedesignated receiving portion 104A of the substrate 104 and previouslydeposited polymerizable mixture 103.

One or more actinic radiation source(s) 105 and 106 (which may containLEDs emitting a same or different wavelengths of energy).

Some variants of the present invention include an enclosure 114 with oneor more ports 107 and 108 for providing a controlled atmosphere 109within the enclosure 114. The enclosure 114 may contain an atmospherethat is ambient to and encompassing one or more of: the substrate 104,print devices 101-102, droplets 110 polymerizable mixture (which arepositioned to form an ophthalmic lens, such as a contact lens) fromdeposited polymerizable mixture 103 which has been built up on thesubstrate, and a source of actinic radiation 105-106 .

In some embodiments, the substrate 104 may be positioned proximate to,such as beneath, at least one 3D-printing device 101-1-2. Therelationship of beneath or underneath is derived from a direction ofgravity. The print devices 101-102 are operative to dispense droplets ofpolymerizable mixture 110 onto a receiving surface 103A. The receivingsurface 103A may include one or more of: a surface of the receivingportion 104A of the substrate 104; a surface of previously depositedpolymerizable mixture 103; and a receiving portion of an insert, such asa rigid lens or an electronic device. The droplets are deposited in apattern that reproduces an energy transmissibility pattern, such as agrayscale image. Successive depositions of the pattern are aggregated toform a volume of polymerizable mixture in a desired shape of a targetoptical element (e.g., see FIGS. 4,-5 ).

Following the application of the droplets of polymerizable mixture 110to the receiving surface 103A to form a volume of polymerizable mixture103, the polymerizable mixture may be exposed to a first dose of actinicradiation (which will be in a first range of wavelengths and for a firstduration of time and a first intensity (such as, for example,ultraviolet or blue light). In some embodiments, the first range of doseof actinic radiation may be supplied to the deposited polymerizablemixture via a first source of actinic radiation 105. Final cure can beaccomplished via exposure of the aggregated polymerizable mixture to asecond does of actinic radiation (which includes a second range ofwavelengths, a second duration of time and a second intensity) and maybe sourced from a same source of actinic radiation 105 or differentsource of actinic radiation 106. Final cure will allow a formed article,such as an ophthalmic lens 111 to be removed from the substrate.

In some variants of the present invention, a final cure process step mayadditionally be performed in an environment with a controlledtemperature, such as, for example a temperature elevated above anambient room temperature.

According to some embodiments, a first print head 101 of the system 100may provide a first polymerizable mixture and a second print head 102may provide a second polymerizable mixture which may be compositionallythe same or different from the first polymerizable mixture and which mayinclude functional additives or a non-polymerizable mixture (e.g.,functional additives or solvents containing functional additives).

Ambient conditions within the system 100 may be controlled, such as, inparticular with respect to an oxygen content of a controlled atmosphere109, and, in some embodiments, temperature, ambient light, amount ofparticulate, size of particulate, circulation or other ambientatmosphere movement, and almost any variable that may affect one or moreof: a movement of unpinned and unpolymerized deposited polymerizablemixture, polymerization of the deposited polymerizable mixture, and ashape of a device formed by polymerization of the depositedpolymerizable mixture may be controlled.

In conditions where substrate 104 is capable of transmitting actinicradiation or is transparent to actinic radiation, sources of radiation105 and 106 may both, or either, individually or in alternatecombinations, be located beneath or at an angle to substrate 104 as wellas that shown in FIG. 1 . In addition, a shutter or other actinicradiation shield may be located above or on a lateral side of areceiving surface. The shutter or other actinic radiation shieldpositioned and functional to shield the print head from actinicradiation or other actinic condition.

The nature of the ambient gaseous environment can be controlled, forexample, through the use of purging nitrogen gas though the inlets 107,108. Purging can be performed to increase or reduce oxygen partialpressure to predetermined levels.

Referring now to FIG. 2 a schematic diagram illustrates some alternativeaspects that may be incorporated into a 3D additive manufacturing system200. Some of same reference numbers are used as for FIG. 1 (e.g., 3Dprint heads 101 - 102, actinic radiation source(s) 105 and 106,substrate 104, an enclosure 114 with one or more ports 107 and 108, anda controlled atmosphere ambient to deposited polymerizable mixture 110).Additionally, the embodiments illustrated in FIG. 2 include an oxygensensor 204, gate 205 for moving components in and out of the enclosure114, a UV blocking screen 112 and an actuation structure 203 (e.g., abelt drive or stepper motor linear drive) configured to provide movementrelative to the substrate 104 and the one or more 3D print head 101-102and/or movement relative to one or more actinic radiation source105-106.

The 3D printing system 200 illustrated is similar to that of FIG. 1 , asillustrated in FIG. 2 , also includes one or more actuators 201-203configured (and operative) to provide relative movement between thesubstrate 104 and the one or more of: the 3D print head(s) 101-102;actinic radiation source(s) 105-106; and the actinic radiation source(s)105-106, and in some embodiments, blocking screens 112 and/orenclosures. In some embodiments, a print head actuator 201 is configured(and operative) to move one or more of the print heads 101-102 relativeto the substrate 104. Similarly, a radiation source actuator 203 isconfigured (and/or operative) to move one or more actinic radiationsources 105-106 relative to the substrate 104. A substrate actuator 203is configured (and/or operative) to move the substrate 104 relative toone or both of the print heads 101-102 and the actinic radiation sources105-106. Although a belt drive 203A is illustrated as actuationstructure 203 and a stepper motor track illustrated as actuationstructures 201-202, other devices and apparatus are within the scope ofthe present invention. The actuation structures 201-203 may besynchronized such that relative movement between one or more of: thesubstrate 104, print heads 101-102, and actinic radiation sources105-106 can be coordinated with deposition of polymerizable material 110from the print head(s) 101-102.

The processes presented herein, may be practiced on the systems 100, 200described to form an optical element 211. The process may includeoperation of one or more print heads 101-102 with a first print head 101dispensing droplets 110 of a first polymerizable mixture and one or moreadditional print head(s) 102 dispensing droplets 110A of compositionsthat may include: a first polymerizable mixture, a second polymerizablemixture which is compositionally different from said first polymerizablemixture, and a non-polymerizable substance or mixture.

In some embodiments, one or more of: the first polymerizable mixture,the second polymerizable mixture, and the non-polymerizable mixtureinclude one or more functionally active substance, such as, for example,a substance in dissolved form.

Release of the Ophthalmic Device From the Substrate and Post-Treatment

Following sufficient deposition of polymerizable mixture 103 to form anoptical element 211 (e.g., ophthalmic device) and performance of acuring process, the optical element 211 is typically released from thesubstrate. It is preferable that the polymerizable mixture 103 depositedin a specific pattern to form the optical element 211 is sufficientlyphysically bound to the substrate 104 during preparation of the opticalelement 211 to prevent unwanted movement relative to the substrate 104,however, the polymerizable mixture 103 should not be bound so securelythat removal of the optical element 211 from the substrate 104 damagesthe optical element 211. For example, in some embodiments, care shouldbe taken that no covalent bonds are formed between the polymerizablemixture 103 and the substrate 104 during preparation of the opticalelement 211, including the curing of the polymerizable mixture 103.

The ophthalmic device 211 may be released (or otherwise removed) fromthe substrate 104 by physical means so as to be able to manipulate theoptical element 211 in various ways. For example, the optical elementmay be manipulated via one or more of: washing the optical element 211to remove by-products, soaking the optical element 211 in bufferedsaline, tinting, marking and packaging the optical element 211. Forexample, in some variants of the present invention, such as when theoptical element 211 is formed with a hydrogel polymer, the opticalelement 211 may be soaked with one or both of: water, and a solution,such as a buffered saline solution, sufficiently to cause the opticalelement 211 to expand. The expansion facilitates release of the opticalelement 211 from the substrate 104. A solution may also include one morerelease agents. Release agents may include compounds, or mixtures ofcompounds, which, when combined with water, decrease a time required torelease an optical element 211 from the substrate 104, as compared to atime required to release such an optical element 211 using an aqueoussolution that does not include the release agent(s).

Although typically preferred, it is not strictly necessary that thecuring of optical element 211 is completed before release from thesubstrate 104.

In some embodiments, after curing, the optical element 211 is subjectedto one or more extraction process steps to remove unreacted componentsfrom the optical element 211. The extraction process steps may beexecuted using one or more of: conventional extraction fluids, organicsolvents, alcohols; water (or aqueous solutions such as bufferedsaline). In various embodiments, extraction can be accomplished, forexample, via immersion of the lens in an aqueous solution or exposingthe lens to a flow of an aqueous solution. In various embodiments,extraction can also include, for example, one or more of: heating theaqueous solution; stirring the aqueous solution; increasing the level ofrelease aid in the aqueous solution to a level sufficient to causerelease of the lens; mechanical or ultrasonic agitation of the lens; andincorporating at least one leach aid in the aqueous solution to a levelsufficient to facilitate adequate removal of unreacted components fromthe lens. The foregoing may be conducted in batch or continuousprocesses, with or without the addition of heat, agitation or both. Theophthalmic device may also be sterilized by known means such as, but notlimited to, autoclaving and radiation sterilization. Sterilization maytake place before or after packaging the optical element 211 in asuitable storage container, preferably after packaging. In somepreferred embodiments, the optical element 211 is packaged in an aqueoussolution.

For optical elements 211 formed with hydrogels, the packing may includepacking in a physiological saline solution with around 0.9% sodiumchloride and suitable buffering agents such as phosphate or boratebuffer systems. In addition, the packing solution may include one ormore functionally active substances including biologically activesubstances.

Aqueous solutions may also include additional water soluble componentssuch as release agents, wetting agents, lubricating agents, activepharmaceutical ingredients (API), vitamins, antioxidants andnutraceutical components, combinations thereof and the like. In someembodiments, the aqueous solutions comprise less than 10 weight-%, andin others less than 5 weight-% organic solvents such as isopropylalcohol, and in another embodiment are free from organic solvents.Depending upon a composition of the aqueous solution. The aqueoussolution may or may not require special handling, such as purification,recycling or special disposal procedures.

In some embodiments, an aqueous content of a hydrogel optical element211 includes at least 30 weight-% water, in some embodiments at least 50weight-% water, in some embodiments at least 70 weight-% water and inothers at least 90 weight-% water.

In variants of the present invention, a polymerizable mixture 110comprises hydroxyethyl methacrylate (HEMA) monomers, and the methodcomprises the subsequent step of swelling the optical element,preferably an ophthalmic device, in water, whereby the optical elementobtains a water content from 10 to 80 weight-%, and preferably from 35to 70 weight-%.

In embodiments, the polymerizable mixture 110 comprises acrylatemonomers not including HEMA monomers, and the method comprises thesubsequent step of swelling the optical element, preferably anophthalmic device, in water, whereby the optical element obtains a watercontent from 10 to 80 weight-%, and preferably from 35 to 70 weight-%.

In embodiments, the polymerizable mixture 110 comprises reactivesilicone precursors, and the method comprises the subsequent step ofswelling the optical element, preferably an ophthalmic device, in water,whereby the optical element obtains a water content from 5 to 70weight-%, and preferably from 10 to 50 weight-%.

Novel Ophthalmic Devices

The methods and apparatus of the present invention enable the formationof an optical element 211 with previously unobtainable designs, such as,by way of non-limiting example, one or more of: a contact lens orintraocular lens with a non-rotationally symmetrical surface, withcorresponding optical corrections, including very steep radii ofcurvature and very high spherical and cylindrical corrective components;a contact lens or intraocular lens including multiple spherical andcylindrical corrections within the same lens as opposed to a singlespherical corrective power reflecting the power distribution map of theeye and not just the average corrective power of refractive power from aphoropter or refractometer; and a contact lens or intraocular lenscapable of (due to non-rotational symmetry) correcting opticalaberrations resulting from poor surgical outcomes of PRK or LASIK orLASEK surgery or from aberrations due to an unusual corneal surface.

Repetitive Grayscale Image Based Additive Manufacture

Referring now to FIG. 3 , an exemplary energy transmissibility pattern,such as a grayscale image 300, may be used to create additivemanufacturing control commands to control release of droplets ofpolymerizable mixture in a pattern that replicates the grayscale image300.

For example, in some embodiments, a map of data that either directly orthrough conversion represents an amount of deposition of polymerizablemixture at a given location that corresponds with data values associatedwith pixels included in a grayscale image 300, such as, for example, aninteger map. In other embodiments, a value associated with a pixel maybe a float point or other expression of a whole number of a real number.The data values may correspond with an amount of energy transmissibilityat a pixel location and the data values may be accessed electronicallyand a processor executing software commands may convert the data valuesto additive manufacturing printhead control commands. The printheadcontrol commands are executable to control a deposition of apolymerizable mixture at locations that correspond to the patternreplicating the grayscale image 300 on a pixel by pixel basis. Forexample, a data value with a relatively larger digital number maycorrespond with a darker area of the grayscale image 300 and maycorrespond with an emission of a greater amount of polymerizable mixturefrom a print head than an emission corresponding with a lighter area ofthe grayscale image. The greater amount of polymerizable mixture than ato a thicker deposit 301 and a value of a control command may beassigned by conversion of a grayscale value at the location of a thickerdeposit 301 to a control command value of the printhead for a thickerdeposit 301. Likewise, a lighter value included in the grayscale maycorrespond to a thinner deposit 301A and a value of a suitable printheadcontrol command may be assigned by conversion of the lighter grayscalevalue to an appropriate control command value for a thinner deposit301A.

In some examples, the thicker deposit 301 may be formed by printing arelatively larger amount of polymerizable mixture on a particularlocation of a receiving surface during a pass of 3D printhead over thereceiving surface being printed upon, and a thinner deposit 301A maycorrespond with printing a relatively lesser amount of polymerizablemixture at a position of a thinner deposit 301 A. A thicker amount 301may correspond with a relatively darker portion of a grayscale image 300and a thinner amount 301A may correspond with a relatively lighterportion of the grayscale image 300.

According to the present invention, following each pass of the printhead and associated polymerizable mixture deposition, the depositedpolymerizable mixture may be allowed to “sit” for a short period duringwhich the material will be acted upon by physical forces, such asgravity, surface tension and microforces to modify surfacecharacteristics. Modifying surface characteristics, may include, by wayof non-limiting example, one or more of: leveling out high and low areasformed during the deposition process; smoothing a surface of thedeposited polymerizable mixture; flowing deposited polymerizable mixtureinto interstitial areas; and form a uniform edge of depositedpolymerizable mixture.

Essentially, the present invention allows for an upper surface 302 thatis formed by physical forces existing in nature, as opposed to amanufactured surface, such as a mold surface and/or a lathed surface.Gravity will smooth an upper surface of deposited polymerizable mixtureprior to the deposited polymerizable mixture undergoing a gelationprocess, such as, for example, the deposited polymerizable mixture beingpinned by exposure to a controlled amount of actinic radiation.

In some variants of the present invention, a control command may be usedto determine how many passes a 3D printhead has made over a receivingsurface. A number of passes of the 3D printhead may correlate with athickness of polymerizable mixture deposited and also correlate with anamount of energy transmissibility at particular locations of a patternof deposited polymerizable mixture. In this manner, depositedpolymerizable mixture may be deposited, pinned and ultimately cured in ashape and volume suitable to form an ophthalmic lens with desiredophthalmic qualities. Deposited polymerizable mixture achievessufficient thickness and suitable shape by repeated application of acorresponding grayscale image.

In some variants of the present invention, each pass of the 3D printheadmay print a pattern of polymerizable mixture corresponding with a samegrayscale image, in other embodiments, a different pass of the 3Dprinthead may correspond with a different grayscale image than aprevious pass. As mentioned previously, in some variants of the presentinvention, each pass of a 3D printhead depositing polymerizable mixturemay be followed by exposures of the polymerizable mixture to a gelationprocess, such as an amount of actinic radiation, thermal activation, orthe like, that is sufficient to partially polymerize the depositedpolymerizable mixture. A curing process may be completed after a finalpass of polymerizable mixture completed. In various embodiments, a finallayer may be exposed to a pinning step, and/or move directly to a fullcuring process.

Curing and/or pinning may be facilitated by inclusion of one or morephoto initiators with the deposited monomer. Photinitiators may include,by way of non-limiting example, initiators activated by energy of orabout 392 nM and 400 nM.

In some examples, an energy transmissibility pattern (e.g., a grayscaleimage) may be derived from an article in physical form that isprocessed, such as via an optical scanning process, image captureprocess, or photographing process, to capture the energytransmissibility data into an electronic form, such as, for example adigital data value, and the electronic form may be converted to controlcommands.

Some variants of the present invention include a grayscale image with agenerally spherical shape, where the lighter values are associated withthicker deposits. Thus, a different conversion protocol may be assignedto different grayscale images depending on which values corresponds tothick and thin deposits, respectively.

In some examples, a single grayscale image may be used to represent adesired product lens and its associated control commands. The singlegrayscale image is repeatedly deposited in successive passes of the 3Dprinthead, one pass following another until a desired optical quality isembodied in the deposited polymerizable mixture which may be cured toform an article that also meets physical parameters suitable for wearingon an eye of a patient.

In other examples, a series of grayscale images may be assembled tocreate multiple sets of control commands. The control commands mayresult in deposit of different shape designs and physically create anadditive composite of the images. In other examples, multiple grayscaleimages may be combined and processed before any processing occurs. Insome examples, a combination of multiple images may be normalized tocorrespond with upper and lower thickness factors.

In some examples, different features such as edge profiles 303,alignment features, and the like, may be programmed into an opticalelement command protocol by the addition of grayscale images to a lensprofile.

In some examples, a refractive element may be designed at a location ona surface plane as an array of grayscale values, where the valuescorrespond to an added thickness or range of thickness in the printingprocess. In a similar example, a constant grayscale value may equate toa plano lens element with no refractive power add to any underlyingstructure.

In some examples, a grayscale image may be referenced from numerousfiletypes such as, by way of non-limiting example, one or more of: jpeg,tiff, bmp, png and the like, may be used to create a control commandprotocol to print a desired article, such as an ophthalmic lens article,by varying an amount of polymerizable mixture that is deposited atdisparate locations thereby resulting in with more polymerizable mixturedeposition in areas targeted for thicker deposits. The result ofprinting an entire pattern may result in an article with no interstitialareas.

In some variants of the present invention, a grayscale in an image oradditive combination of images, may correspond to processing of multipledisparate passes of a 3D print head, wherein an amount of polymerizablemixture deposited in specific locations and subjected to a pinningprocess before a next deposition pass is completed. A polymerizablemixture deposited during a printing process pass may be a monomermixture with various included photo initiators. One of the photoinitiators may be associated with a wavelength of actinic radiationexposure during an associated pinning processes. After multiple printingpasses have been processed, an entire volume of polymerizable mixturedeposited on a receiving substrate may be subjected to a curing process.In some examples, the curing process may be exposure to actinicradiation of a different wavelength and exposure time, intensity and thelike.

In another aspect, in some embodiments, a grayscale pattern or an energytransmissibility pattern may be dithered via a dithering process oralgorithm prior to generation of a control command for the printheadbased upon the grayscale or energy transmissibility pattern in order togenerate a smoother image deposited via expulsion of droplets from theprinthead and accumulation prior to curing. Dithering may include, wayof non-limiting example, processes consistent with Floyd-Steinberg,Burkes, Sierra, Two Row Sierra, Jarvis, Stevenson, Arce, or otherprocess.

Referring now to FIG. 4 , an optical element 400 is illustratedaccording to some embodiments of the present invention. The opticalelement 400 includes a periphery portion 401 that may be printed orotherwise formed before an optical zone portion 402 of the opticalelement 400. A lens carrier portion 403 may transition the optical zoneportion 402 and the periphery portion 401. The carrier portion 403 ispreferably of a size and shape conducive to comfortably maintaining acompleted lens in place on a wearer’s eye. During additive manufacturingof the optical element 400, polymerizable mixture included in theperiphery portion 401 may be deposited and pinned, but not fullypolymerized, before the polymerizable mixture included in the opticalzone portion 402 is printed and pinned. In some preferred embodiments,the periphery portion 401 may include a greater mass so that as thepolymerizable mixture cures into a polymer, stresses resulting from thepolymerization process will not deform the optical zone portion 402 dueto stabilizing influence of the greater mass of the periphery portion401.

In some embodiments, the periphery portion 401 may remain with theoptical element 400 and form a comfortable edge feature. In otherembodiments, some or all of a periphery portion 401 may be removed, suchas, for example via laser trimming.

Embodiments that include a higher mass periphery zone portion 401 may beformed via the steps of: a) printing or otherwise depositingpolymerizable mixture in the periphery zone portion (which, for aspherical lens may have a generally annular, and other lenses acorresponding perimeter shape such as an oval shape or almond shape); b)pinning the polymerizable mixture in the periphery zone portion 401,wherein pinning will preferably occur after each pass of a print headdepositing monomer; c) printing or otherwise depositing polymerizablemixture in an optic zone; pinning the polymerizable mixture in the opticzone; and curing the deposited polymerizable mixture. Some embodimentsmay additionally include placing a cap in the optic zone to provide anoptic quality.

Referring now to FIG. 5 , a profile cutaway view with a peripheryportion 501 and a carrier portion 502 supporting an optic zone 503 andan optic insert or cap 504. In some embodiments of the presentinvention, the periphery portion 501 may include a higher mass than acarrier portion 502 and/or optic zone 503 portion of the lens 500.

Axial Thickness Profile Generation

The hydrated contact lens front surface radius of curvature (R_(F)) isgenerated from the thick lens formula using the in-air lens power (P),lens index of refraction (n), center thickness (CT), and back surfaceradius of curvature (R_(B)).

The thick lens formula may include, by way of non-limiting example: Theeffective focal length for a thick lens with respect to the principalplanes is given by

$\frac{1}{f} = \left( {n - 1} \right)\left\lbrack {\frac{1}{R_{1}} - \frac{1}{R_{2}} + \frac{\left( {n - 1} \right)d}{nR_{1}R_{2}}} \right\rbrack$

and the distances from the lens vertices to the principal planes are

$\begin{matrix}{h_{1} = - \frac{f\left( {n - 1} \right)d}{R_{2}n}} & {h_{2} = - \frac{f\left( {n - 1} \right)d}{R_{1}n}}\end{matrix}$

For an ophthalmic lens, exemplary variables may include:

R₁ = R_(F)(m)

h₁ = h_(F)

R₂ = R_(B)(m)

h₂ = h_(B)

d = CT(m)

$\frac{1}{f} = \text{P}$

${}^{R_{F}:}\quad_{R_{F} = \frac{{({n - 1})}{({nR_{B} + {({n - 1})}CT})}}{nR_{B}P + n{({n - 1})}}}$

Front and back optic zone surfaces may be generated from front and backradii of curvature and center thickness of the ophthalmic lens otheroptical element.

Exemplary surfaces are shown for a -3.0D design with a 0.1008 mm centerthickness, a 9.1 mm back radius of curvature and an index of refractionof 1.4055 are shown in FIG. 6 .

In some embodiments, an axial thickness profile may be generated bysubtracting a back surface position from a front surface position formultiple radial positions.

A ratio of a hydrated lens to an unhydrated lens may vary based upon thelens material and hydrated lens is 1.4 times larger in each directionthan the un-hydrated lens. Therefore, an un-hydrated axial thicknessprofile may be about 1.4 times smaller than an axial thickness profilegenerated from the hydrated lens front and back surfaces (as usedherein, the term about may be within 10% of a stated amount). Also,radial positions may be about 1.4 times smaller for the un-hydratedlens.

Referring now to FIG. 6 , a graphical representation 600 of an opticalzone front curve surface 603 and back curve surface 604 of a hydratedophthalmic lens is illustrated.

The graphical representation 600 includes a first axis with a scale of ahydrated surface position 601 and a second scale with a hydrated radialposition 602. A first curve maps values of a front curve 603 and asecond curve maps values of a back curve 604 of an ophthalmic lens opticzone.

Referring now to FIG. 7 , a graphical representation 700 of anun-hydrated ophthalmic lens optical zone axial thickness profile 703 isillustrated. In preferred embodiments, an axial thickness profile may beadequately described by an even 4^(th) order polynomial. Thecoefficients from this model may be referenced to generate an opticalzone portion of grayscale print pattern, or other energytransmissibility or energy intensity map pattern.

The graphical representation 700 includes a first axis with a scale ofan unhydrated axial thickness 701 and a second scale with an unhydratedradial position 702. A curve maps values of axial thickness 703 of anophthalmic lens optic zone, with numerical values correlating with thethickness 704 displayed in the middle of the graphical representation700.

For astigmatic lenses, optical power is different for differentdirections (meridians) in the optical zone. For example, a-2.75D/-4.5DX90 has a power of -2.75D in a vertical direction and -7.5Din a horizontal direction. A resulting axial thickness profile may varymeridian within the optical zone and is ‘flattest’ in the verticaldirection and ‘steepest’ in the horizontal direction.

Referring now to FIG. 8 , a false color image of a thickness profile 800is illustrated for an optic zone, where ‘a first intensity 801represents small thickness, and fourth intensity 804 represents an areawith a relatively large thickness. One or more intermediate thicknesses802- 803 may also be included, such as a first intermediate thickness802 and a second intermediate thickness 803. Each thickness may beachieved by depositing an appropriate amount of polymerizable mixture inthe respective positions indicated by the thickness profile 800,allowing the polymerizable mixture to settle, pinning the settledpolymerizable mixture in place via a gelation process, and finallycuring the deposited and pinned polymerizable mixture.

A horizontal (most negative power) and vertical (most positive power)axial thickness profiles may be modeled by even 4^(th) order polynomialsand the coefficients used to generate an optical zone grayscale printpattern represented by the thickness profile 800.

Energy Transmissibility Print Pattern Generation

In some embodiments, an energy transmissibility print pattern (which maybe a grayscale print pattern or other representation of energyintensity) may include two (2) or more regions: an optical zone 801-804(as illustratively defined by the axial thickness profile); and aperiphery 805. Other regions may also be included, such as a region thatcontains a medicament or other leachable substance. Each region may bedefined by various methods. For example, by way of non-limiting example,a pixel size of the print pattern may be specified to be about 0.021 mm.An un-hydrated lens diameter may be, for example 10.0 mm. A number ofpixels in the X & Y directions is defined by the relationship:

$n_{pixels} = 2 \ast round\left( \frac{Diameter}{2 \ast pixel\mspace{6mu} size} \right) + 1$

This definition ensures that n_(pixels) is odd, so that the center ofthe lens is at a center of a print pattern.

A number of grayscale levels may also be specified, such as, forexample, a print pattern of 8 bits (255 gray levels.) It is within thescope of this invention for both of these values to be changed which mayeffect a quality of a printed lens.

Spheres

A spherical lens includes an optical zone that is generally rotationallysymmetric (within 10% of symmetry) and may be defined, for example, byusing an un-hydrated lens center thickness, and the coefficients fromthe even 4^(th) order model:

$\begin{array}{l}{thickness\left( {mm} \right)\left( {x,y} \right) = CT\left( {mm} \right) + C_{2}\left( {mm^{- 1}} \right)r\left( {mm} \right)^{2} +} \\{C_{4}\left( {mm^{- 3}} \right)r\left( {mm} \right)^{4},} \\{r\left( {mm} \right) = pixelSize\left( {mm} \right) \ast sqrt\left( {\left( {x - x_{0}} \right)^{2} + \left( {y -} \right)} \right)\left( \left( y_{0} \right)^{2} \right),}\end{array}$

where (x₀,y_(x)) is the print pattern center. Other variations are alsowithin the scope of the invention.

A center thickness (CT) used to generate a thickness profile may bebased upon a hydrated thickness to the number of layers to be printedtimes the layer thickness. Thus, if a hydrated lens CT is 0.120 mm, thenumber of layers to print is 6, and the layer thickness is 0.012 mm, theCT used to generate the print pattern is 0.120 mm - 0.72 mm = 0.048 mm.

In some preferred embodiments, this may be done to ensure that a ratioof a ‘brightest’ to ‘darkest’ pixel in the pattern remains in anacceptable range for printing. In other embodiments, images may beconverted by print head controller software to binary images. If a rangeof grayscales is too large, ‘bright’ regions may not have enough ‘dark’pixels to create a smooth lens surface.

A thickness may be calculated for pixels where r is less than theun-hydrated optical zone semi- diameter (r_(max)), typically 4.0 mm/1.4(~ 2.857 mm.)

A periphery 805 is the region where r(mm) is outside the optical zone801-804, but within a lens diameter. Many different methods may be usedto define a thickness profile of the periphery. For example, in somepreferred embodiments, patterns use a thickness at the edge of theoptical zone for all pixels in the periphery. Alternate methods mayinclude one or more of: linearly tapering the thickness from the valueat the edge of the optical to a value defined at the ‘edge’ of the lens;and tapering the thickness from the value at the edge of the optical toa value defined at the ‘edge’ of the lens using a higher orderpolynomial, or conic section; adding a ‘stiftening’ ring to theperiphery to improve lens handling; tapering using different methods indifferent zones of the periphery; and a combination of tapering and a‘stiffening’ ring.

Torics (Astigmatic Lenses)

An optical zone may not rotationally symmetric and may be defined usingan un-hydrated lens center thickness, the two (2) sets of coefficientsfrom the even 4^(th) order models of the most positive and most negativepower meridians, and a desired angle in a print pattern of a mostpositive power meridian.

For example, in some embodiments, print patterns may be generated viscalculating the ‘effective’ 2^(nd) order coefficient for each principlemeridian:

C_(2, effective)(mm⁻¹) = C₂(mm⁻¹) + 0.5C₄(mm⁻³)r_(max)(mm)⁴

The ‘equivalent’ r₂ coefficient is defined as the average of the two (2)effective coefficients. The astigmatic coefficient is defined as:

C_(2, 2)(mm⁻¹) = 0.5(C_(2, effictive, minus)(mm⁻¹) − C_(2, effective, plus)(mm⁻¹)),

where C_(2,effective,plus) is the effective second coefficient of themost positive meridian, and

C_(2,effectiive,minus) is the effective second coefficient of the mostnegative meridian.

For each pixel in the lens print pattern, the distance from the lenscenter (r(x,y)) and the angle in standard Cartesian coordinates (0(x,y))are calculated.

An optical zone thickness may be defined as:

$\begin{array}{l}{thickness\left( {mm} \right)\left( {x,y} \right)} \\{= CT\left( {mm} \right)} \\{+ \left( {C_{2,equivalent}\left( {mm^{- 1}} \right) + C_{2,2}\left( {mm^{- 1}} \right)\cos\left( {\vartheta\left( {x,y} \right) + \varphi} \right)} \right)r\left( {mm} \right)\left( {x,y} \right)^{2},}\end{array}$

where φ is the angle of the most positive meridian.

A thickness at the edge of the optical zone varies with angle. For toricprint patterns, a transition zone may be generated to produce a singlethickness value for all angles. The transition zone may be an annulus0.5 mm wide for the hydrated lens (0.5 mm/1.4 for the un-hydrated lens.)A target thickness for the transition may be equal to a minimumthickness at the optical zone boundary and may essentially be equal to:

thickness_(target)(mm) = CT(mm) + (C_(2, equivalent)(mm⁻¹) + C_(2, 2)(mm⁻¹))r_(OZ)(mm)²

The thickness for each pixel in the transition region is defined as alinear function of its radial position. The thickness at the opticalzone edge is defined for each pixel in the transition region as:

$\begin{array}{l}{thickness_{OZ\mspace{6mu} Edge}\left( {mm} \right)\left( {x,y} \right)} \\{= CT\left( {mm} \right)} \\{+ \left( {C_{2,equivalent}\left( {mm^{- 1}} \right) + C_{2,2}\left( {mm^{- 1}} \right)\cos\left( {\vartheta\left( {x,y} \right) + \varphi} \right)} \right)r_{OZ\mspace{6mu} Edge}\left( {mm} \right)\left( {x,y} \right)^{2}}\end{array}$

A slope for each point is defined as:

$slope\left( {x,y} \right) = \frac{thickness_{OZ\mspace{6mu} Edge}\left( {mm} \right)\left( {x,y} \right) - thickness_{target}\left( {mm} \right)}{width_{transition}\left( {mm} \right)}$

The intercept for each point is defined as:

intercept(mm)(x, y) = thickness_(target)(mm) − slope(x, y)r_(transition end)(mm)

A thickness for each point in the transition region is:

thickness(mm)(x, y) = intercept(mm)(x, y) + slope(x, y)r(mm)(x, y)

Referring now to FIG. 9 , an exemplary graphical image of a transitionregion is illustrated. A periphery axial thickness profile 900 isdefined by a linear change from the end of the transition zone 904 to aminimum axial thickness in the optical zone 901. The slopes andintercepts for the periphery points 902-903 are defined in the samemanner as was used to define the transition zone, only using the end ofthe transition zone and minimum thickness for the edge of the opticalzone thickness and the end of the transition zone thickness,respectively. All pixels outside the lens diameter may be set to 0.

FIG. 10 illustrates a thickness profile for a periphery region 1000 ofan ophthalmic lens with multiple variant thicknesses 1002-1004 on theperiphery region of an optic zone 1001.

FIG. 11 illustrates a thickness profile a full ophthalmic lens 1100. Theillustrated thickness profile includes lens portions 1101-1105 thatcomprise an optic zone 1101-1104 and a periphery region 1105. Each ofthe lens portions 1101-1105 include one or more pixels 1106 (shown in ablown up view). Each pixel 1106 may be associated with a thickness.

Print Pattern

In some embodiments of an energy transmissibility pattern (e.g., andenergy intensity pattern or grayscale pattern) that correspond with aprint pattern, ‘bright’ pixels may represent unprinted areas and ‘dark’pixels represent areas which receive deposited polymerizable mixture. An‘intensity’ of ‘dark’ pixels corresponds to a desired thickness of aresulting ophthalmic lens at that position.

In some exemplary embodiments, a print pattern ‘intensity’ of the lensmay be defined as:

$intensity\left( {x,y} \right) = 255 - floor\left( \frac{255 \ast thickness\left( {mm} \right)\left( {x,y} \right)}{\max\left( {thickness\left( {mm} \right)\left( {x,y} \right)} \right)} \right),$

where floor( ) converts the value to the smallest integer.

All pixels outside the lens may be set to 255, such that a smallerintensity value corresponds to a larger thickness, and a smallest valuecorresponds to a smallest thickness.

The value of 255 corresponds to an 8 bit image. If more than 255 graylevels are used, the value of 255 is replaced with the number of graylevels. For example, for a 10 bit image, the value would be 1023.

Referring now to FIG. 12 , method steps for forming an ophthalmic lens,according to some embodiments of the present disclosure, are presentedin a flowchart format.

At step 1202, the methods include positioning a substrate at a firstposition relative to an additive manufacturing print head. The substratemay include a receiving portion that may be planar or arcuate. Thereceiving portion may act as a receiving surface for a first pass of aprint head depositing polymerizable mixture. After a first pass, thereceiving surface will typically include at least some areas withpreviously deposited polymerizable mixture.

At step 1204, the method may include emitting a first pattern ofdeposited droplets of polymerizable mixture from the print head, thepattern of deposited droplets of polymerizable mixture correspondingwith a first portion of an energy transmissibility map of an ophthalmiclens being formed. The pattern is preferably a two dimensional imagethat represents light intensity through a desired optic. The dropletswith emitted at a time designation, such as T1, which may be relative toother time designations. In preferred embodiments, the two dimensionalrepresentation will have a numerical value associated with an X,Yposition (or other coordinate designation). The numerical value willrepresent an amount of light that passes through an optical element at aposition specified by an X,Y axis designation. A print pattern may bebased upon the numerical value, such that, in some embodiments, anamount of polymerizable mixture deposited at a position on a receivingsurface corresponding the X,Y pattern correlates with the numericalvalue (e.g., lighter areas will have a lower X,Y numerical value andwill receive less polymerizable mixture, and darker areas will have ahigher X,Y numerical value and will receive more polymerizable mixture).

Design of an optical element may be accomplished via analysis of a raytrace pattern of how light passes through the optical element. In someembodiments, an X,Y numerical value in turn may be derived from amathematical model of a desired optical element three dimensional shape.

At step 1206, the method may include receiving the deposited droplets ofpolymerizable mixture onto a receiving surface, the receiving surfacemay include one or more of: the substrate; an aggregation ofpolymerizable mixture formed from previously emitted droplets ofpolymerizable mixture; and an insert. The insert may include, forexample, an optical insert, a passive electronic device, an activeelectronic device; and/or a power source, such as a battery, harvestingdevice, or antenna.

At step 1208, at a second time (T2) deposited droplets of polymerizablemixture on the receiving surface may be exposed to a pinning process.The pinning process will cause partial polymerization of the depositeddroplets of polymerizable mixture. Preferably the partial polymerizationresults in a viscous aggregation of partially polymerized mixture thatis resistant to flow but may integrate with subsequently depositedpolymerizable mixture.

At step 1210, the method may include repositioning the substrate (anddeposited polymerizable mixture) to a next position (position plus N)relative to the print head.

At step 1212, the method may include emitting a next pattern ofdeposited droplets of polymerizable mixture corresponding with a nextportion of the energy transmissibility map of an item being formed, suchas an ophthalmic lens being formed.

In various implementations of the present invention, the method mayinclude repeating steps multiple times. For example, there may bemultiple passes of the print head relative to the substrate, andmultiple dwell times allowing gravity to act on at least some of thedeposited droplets of polymerizable mixture to smooth a surface of thedeposited polymerizable mixture and fill interstitial spaces between thedeposited droplets and aggregating of deposited material with materialalready deposited and pinned. Accordingly, at step 1214 a next patternof droplets of polymerizable material may be emitted. The pattern may asame pattern as a previous pattern or a different pattern.

At step 1218, polymerizable material deposited in a current pass of aprint head may be integrated with material on the receiving surface,such as material previously deposited. In some embodiments, theintegrated material may form a single volume of polymerizable mixture onthe substrate.

At step 1220, gravity may be allowed to act on at least some of thedeposited droplets of polymerizable mixture to smooth a surface of thedeposited polymerizable mixture and fill interstitial spaces between thedeposited droplets and aggregating of deposited material with materialalready deposited and pinned.

At step 1222, the method may include curing the deposited droplets ofpolymerizable mixture.

In some embodiments, a pinning process may include exposing thedeposited droplets of polymerizable mixture to a first wavelength ofactinic radiation for a limited amount of time sufficient to casegelation of the deposited droplets of polymerizable mixture and notcause curing of the deposited droplets of polymerizable mixture.Similarly, in some embodiments, a cure process may include exposingdeposited polymerizable mixture to a second wavelength of actinicradiation for a sufficient time and of sufficient intensity to causepolymerization of the deposited droplets of polymerizable mixture. Someembodiments may also include facilitating a cure process by an increasein ambient temperature.

Referring now to FIG. 13 , a schematic diagram illustrates deposition ofone or more polymerizable mixtures 1302 from one or more print head(s)1301 to form an ophthalmic lens 1307. The print head 1301 depositspolymerizable mixture 1302 until a volume of polymerizable mixture 1303is formed on a receiving area 1306 of the substrate 1305 in a patternthat replicates a 2D pattern used to generate control commands for eachpass of the print head 1301 in relation to a position of the substrate1305. At least some of the receiving area 1306 of the substrate 1305will act as a receiving surface of the deposited polymerizable mixture1302 until a volume of deposited polymerizable mixture 1303 covers afootprint area for a design of the ophthalmic lens 1307.

As stated herein, in some preferred embodiments relating to opticalelements, amounts of polymerizable mixtures 1302 deposited from a printhead 1301 to form an ophthalmic lens 1307, vary in accordance with atwo-dimensional pattern that represents an integer map of energyintensity (which may represent transmissibility of energy through theophthalmic lens).

The pattern is preferably a two dimensional image that represents lightintensity through a desired ophthalmic lens 1307. In preferredembodiments, the two dimensional representation will have a respectivenumerical value associated with multiple X,Y positions. The numericalvalue may represent an amount of light that passes through theophthalmic lens 1307 at a given position specified by an X,Y axisdesignation.

Control commands to the print head cause the print head 1301 to depositpolymerizable mixture 1302 based upon a two dimensional print patternspecifying an amount of polymerizable mixture 1302 deposited at a givenX,Y position. After multiple successive passes of depositing thepolymerizable mixture 1302, a volume of polymerizable mixture 1303 onthe substrate 1305 possesses a three dimensional shape representative ofthe mathematical model of the desired ophthalmic lens.

The two dimensional print pattern of an amount of polymerizable mixturethat represents an amount of light that passes through the ophthalmiclens 1307 at a given position specified by an X,Y axis designation mayalso correlate with an amount of polymerizable mixture 1302 deposited ata position on the receiving surface 1304 (e.g., lighter areas of the twodimensional print pattern will have a lower X,Y numerical value and willreceive less polymerizable mixture, and darker areas will have a higherX,Y numerical value and will receive more polymerizable mixture).

In some embodiments, a design of an ophthalmic lens may be accomplishedvia analysis of a ray trace pattern of how light passes through theophthalmic lens. Preferably, an X,Y numerical value in turn may bederived from a mathematical model of a three dimensional shape of adesired ophthalmic lens.

According to the present invention, the two dimensional print patternspecifying an amount of polymerizable mixture deposited at a given X,Yposition is printed multiple times in successive passes of the printhead relative to the substrate 1305. Deposited polymerizable mixture1302 is received onto a receiving surface 1304. The receiving surface1304 may include one or both of: a volume of previously depositedpolymerizable mixture 1303, and a receiving area 1306 of the substrate1305.

Deposited polymerizable mixture 1303 undergoes a pinning and/or gelationprocess to form a volume of gelled polymerizable mixture 1303. Thevolume of gelled polymerizable mixture 1303 is polymerized sufficientlyto prevent (or at least substantially slow a movement of) thepolymerizable mixture that has been received onto the receiving surfacewhile allowing subsequently deposited polymerizable mixture 1302 to meldwith previously deposited (and pinned) volume of polymerizable mixture1303 and form a structure with a single mass of polymerizable mixture.In preferred embodiments, melding may include intermingling with, orbecoming interspersed with, the volume of previously deposited andpinned polymerizable mixture 1303 such that individual layers orstriations of deposited polymerizable mixture 1302 are not discernablein a volume of polymerizable mixture 1303 formed on a receiving area1306 of the substrate 1305 once the volume of polymerizable mixture 1303is cured. Such embodiments may be preferred since unwanted diffractionmay be an optical quality resulting from successive steps or otherinterlayer artifacts associated with disparate layers of polymerizedmaterial being present in an ophthalmic lens.

Prior to pinning, gravity may act on a surface 1304 of the volume ofpolymerizable mixture 1303 to smooth the surface 1304 and fillinterstitial aberrations in the surface and thereby improve opticalqualities of a resulting ophthalmic device (as compared to a surface ofa machined lens and/or a lens formed from a machined mold part).

Curing of the volume of polymerizable mixture 1303 follows dispositionof droplets polymerizable mixture 1302 during a final pass of theprinthead 1301 and the substrate 1305. Curing may be processed byexposure of the volume of polymerizable mixture 1303 to actinicradiation and/or heat sufficient to cause a substantially completepolymerization of the volume of polymerizable material 1303.

As illustrated, FIG. 13 shows a printhead 1301 that is essentiallyperpendicular to an apex 1308 of deposited polymerizable mixture 1303.In various embodiments, droplets polymerizable mixture 1302 may (or maynot) follow a trajectory that is perpendicular to the apex 1308 of areceiving surface, which may include one or more of the substrate, 1305,a receiving area 1306 and a surface of the previously depositedpolymerizable mixture 1303.

Referring now to FIG. 13A, a printhead 1301 illustrated moving in adirection 1309 of a printing path. Droplets of polymerizable mixture1302A will follow a droplet trajectory 1309 influenced by the speed anddirection of the printhead 1301 at a time of release of the droplets ofpolymerizable mixture 1302A. The droplet trajectory 1309 will have aspeed and direction of its own. According to the present invention, insome embodiments, a printhead 1301 and a droplet trajectory 1309 may beat an angle other than a right angle to the surface of the apex of areceiving surface 1304 for some (e.g., a majority) of the droplets ofpolymerizable mixture 1302A will integrate into the previously depositedpolymerizable mixture 1303A and be pinned and ultimately cured. In thismanner, the present process differs over previously known processes thatrequire a small portion of additive manufacture material to be placed ona surface in an incremental manner and not become integrated intopreviously deposited material before being cured.

Referring now to FIG. 14 , an exemplary dynamic shape of a droplet ofpolymerizable mixture 1401 is illustrated at various times 1402 afterrelease from a printhead. According to the present invention, the shapeof the droplet 1401 may vary based upon a speed of travel of the droplet1401 through an ambient atmosphere. In some preferred embodiments, anarticle formed by the processes disclosed herein are generally notinfluenced by a shape of the droplet of polymerizable material 1401. Therelatively small mass of each droplet 1401 and the integration ofdroplet into other polymerizable material on a receiving surfaceessentially make a shape of a manufactured article unaffected by a shapeof individual droplets 1401, or a changing shape of the droplet 1401 atvarious times 1402 after release by the print head (not shown in FIG. 14).

Referring now to FIG. 15 a flowchart 1500 illustrates exemplary methodsteps that may be executed in some implementations of the presentinvention.

At step 1501 the process may include positioning a substrate at firstposition relative to an additive manufacturing print head.

At step 1502 the process may include emitting a first pattern ofdeposited droplets of polymerizable mixture from a print head, the firstpattern of deposited droplets of polymerizable mixture correspondingwith a first portion of a grayscale image.

At step 1503, the process may include receiving the deposited dropletsof polymerizable mixture on a receiving surface, the receiving surfacemay include one or more of the substrate; previously emitted droplets ofpolymerizable mixture; and an inserted article. The inserted article mayinclude, by way of non-limiting example, one or more of: an opticalelement, such as a rigid permeable lens, an electronic device, and apower source.

At step 1504, the process may include repositioning the substrate to anext position relative to the print head. Repositioning may includemoving one or both of the substrate and the print head relative to theother.

At step 1505, the process may include emitting a next pattern ofdeposited droplets of polymerizable mixture from the print headcorresponding with a next portion of the grayscale image.

At step 1506, the process may include allow physical forces, such asgravity to act on the deposited droplets of polymerizable mixture.

At step 1507, the process may include integrating at least some of thedroplets to form a combined volume of polymerizable mixture on thesubstrate.

At step 1508, the process may include exposing the deposited droplets ofpolymerizable mixture on the receiving surface to a pinning processcausing partial polymerization of the deposited droplets ofpolymerizable mixture.

At step 1509, the process may include repeating positioning anddeposition steps for multiple passes of the print head relative to thesubstrate.

At step 1510, the process may include curing the combined volume ofpolymerizable mixture to form an ophthalmic lens.

The process may include, following each pass of the print head relativeto the substrate, integrating at least some of the droplets ofpolymerizable mixture deposited during a current pass with polymerizablemixture previously deposited onto the receiving surface to form acombined volume of polymerizable mixture on the substrate.

At step 1511, the process may include releasing a formed ophthalmic lensfrom the substrate.

EXPERIMENTAL DETAILS Method for Determining Water Content of HydrogelDevices

The water content for hydrogel devices (e.g., contact lenses) may bedetermined as described in: ISO/DIS 18369-4:2016 in Section 4.6(Gravimetric Method given in 4.6.2).

Keratometry Measurements

A keratometer measures the central radii of the cornea and in this casethe central radii of the front of the non-hydrated hydrogel parts formedon PMMA domes. (see experimental section on 3-D printing on PMMA domes).The instrumentation used was the auto-keratometer from Nidek modelARK900S. The support was set on a horizontal platform and wedges addedto align the center and the axis of the PMMA dome bearing the hydrogelsurface with the center and axis of the keratometer. In the first set ofmeasurements made which had a large amount of astigmatism the wedgeswere not used, and the astigmatism measured was an artifact due to themeasurements being made off axis.

Radii of Curvature Measurements

Contact lens power depends upon the combination of the powers of thefront and back surfaces of the contact lens modulated by the refractiveindex of the material and contact lens thickness. The powers of thefront and back surfaces of the contact lens depend upon the radii ofthese surfaces.

The relationship between the power and the radius in air isPower=(Contact lens refractive index-1)/Radius; the power is in dioptersand the radius in meters.

For the front surface, the radius is defined in ISO1 8369-1;2006 (E)(2.1.2.2.5) as the radius of curvature of tire front optic zone of asurface with a single refractive element.

The radii of curvature of the front of the PMMA domes were measured withan auto-keratometer also known as ophthalmometer which is one of themethods prescribed in ISO DIS 18369-3:2016 (Annex C). The ophthalmometermethod measures the reflected image size of a target placed at a knowndistance in front of a rigid or soft lens surface and the relationshipbetween curvature and magnification of the reflected image is then usedto determine the back optic zone radius. Nevertheless, this method wasused to measure the front surface radii of the PMMA domes.

Light Transmittance

The luminous transmittance is defined in ISO 18369-1:2006 (E). Thevalues presented in the table further below for luminous transmittancerepresent the mean between 380 nm and 780 nm. The method of measurementis detailed in ISO DIS18369-3:2106 (4.8.2).

Apparatus and Materials

To demonstrate the principles of the invention a series of experimentswere carried out. The experiments were run using:

Raw Materials

-   2-Hydroxyethyl methacrylate (HEMA); 99.9% HEMA with 16 ppm MEHQ;-   Ethyleneglycol dimethacrylate (EGDMA); Assay: 98.0%-   Methacrylic acid (MAA); Assay: 99.0%-   Trim ethylolpropance trimethacrylate (TMPTMA), Technical Grade-   Irgacure 651 photo-initiator from BASF Corp, Southfield, Mi-   Irgacure 819 photo-initiator from BASF Corp, Southfield, Mi-   Glass microscope slides from EMS, Hatfield, Pa. and from Am Scope.-   Tween 80 (polysorbate 80) surfactant-   Reagent grade isopropanol-   Deionized or distilled water-   Sterile Saline Solution from Walgreens or B&L-   Nitrogen gas cylinders (<0.1% oxygen) and/or liquid nitrogen tanks-   Rotovap, glove bags, desiccators, brown bottles, syringes, 5 µm    filters, lint-free towels, standard beakers, weighing scale (0.001 g    accuracy), vacuum pump-   LED Sources and Measuring Instruments-   OMNI lamps with output at 365 nm and 400 nm.-   Omnicure LM 2011 Light meter to measure intensity.-   Honeywell Toxi Pro 544590VD simple gas Oxygen monitor.-   Gauge that reads below 33 millibars of oxygen.

3D Printing Station

Custom built with a) Fujifilm’s Samba printing head and b) a conveyorbelt to move substrate under print heads, then two different sources ofactinic radiation in the form of UV lamps. The entire printing stationis contained in an atmospheric enclosure with gas ports.

Example Series A -----. Preparation of Model Samples

In this series, square samples (10 mm by 10 mm) of uniform thickness ofpolymerized HEMA were prepared and evaluated.

Preparation of Substrate

Three drops of Tween 80 were added to 20 ml reagent grade isopropanoland filtered through a 3.1 µm filter. The glass slides were dipped inthis solution three times and air-dried. Preparation of HydratingSolution

Mixed 5 drops of Tween 80 in 100 mL of deionized water and heated to80-90° C. Preparation of Polymerizable mixtures

PM-1A, PM-1B and PM-1C:

-   HEMA: 97.7%-   EGDMA: 1.6%-   Irgacure 819: 0.2%-   Irgacure 651: 0.5%

PM-2:

-   HEMA: 98.1%-   EGDMA: 1.2%-   Irgacure 819: 0.2%-   Irgacure 651; 0.5%

PM-3A, PM-3B AND PM-3C

Uncatalyzed polymerization mixture samples (PM-1A, PM-1B, PM-1C, PM-2,PM-3A, PM-3B and PM-3C; see above) were prepared by mixing the monomersand crosslinkers in brown bottles and left in the refrigeratorovernight. The final polymerization mixture samples, along with thephoto initiators, were processed in a Rotovap using alternate cycles ofdegassing and nitrogen blanketing. The samples weighed approximately 120grams for each of PM-1A, PM-1B, PM-1C and PM-2. The same quantity foreach of PM-3A, PM-3B and PM3C was approximately 34.5 grams.

The resulting partial pressures corresponding to oxygen concentrationsin the polymer mixture are as per below:

-   PM-1A: <0.5% O2-   PM-1B: 2.0% O2-   PM-1C: 5.0% 02-   PM-2: <0.5% O2-   PM-3A: <0.5% O2-   PM-3B: 2.0% O2-   PM-3C; 8.5% O2

O2 Concentration of <0.5% O2:

A 120 g sample was processed per the following protocol via a Rotovap byalternating 3-4 cycles of degassing to 11.0-12.0 torr (approx. 14.0mbar) and blanketing with Nitrogen at 760 torr. One degassing cycleranged from 5-20 minutes and one blanketing cycle did not exceed 5 mins.

O2 Concentration of 2.0% O2

A 120 g sample was processed to 2.0% O2 per the following protocol via aRotovap by degassing to 72 torr (95 mbar) and blanketing with Nitrogenat 760 torr. The degassing cycle was 49 mins, and the blanketing cycledid not exceed 15 minutes.

O2 Concentration of 5.0% O2

A 120 g sample was processed to 5.0% O2 per the following protocol via aRotovap by degassing to 179 torr (235 mbar) and kept mixing for 45 minfollowed by blanketing with N2 to 760 torr for a period not exceeding 5minutes.

O2 Concentration of 8.0% O2

A 120 g sample was processed to 8.5% O2 per the following protocol via aRotovap by degassing to 300 torr (400 mbar) and kept mixing for 45 minfollowed by blanketing with N2 to 760 torr for a period not exceeding 15minutes.

Settings of LED Sources and Printing Station

Omni lamp at 400 nm was set at 22.0 mms from substrate and intensity setat 4.5 W/cm2 as measured by the light meter in the substrate position.

Omni lamp at 365 nm was set at 123 mms from substrate and intensity setat 0.63 W/cm2 as measured by the light meter. Belt speed for movingsubstrate from the printing station to the UV station was set at 40ft/min.

A 10 mm by 10 mm square design of the polymerizable mixture was printed.UV pinning or gelation (stringy/tacky to touch) occurred after 30 sec.(3 cycles of 10 sec.) of exposure to the 400 nm lamp. Measured thicknessof the layer was about 24 µm. Several experiments were previouslyconducted at different intensity settings and exposure times to selectthe condition.

3D Printing Conditions

For UV pinning, at 2400 dpi, printing a layer and exposing to the 400 nmlamp for 30 sec. was done 6 times. Following this, the pinned or gelledsample was exposed for 120 sec. under the 365 nm lamp to cure thesample.

Oxygen concentration was measured by two oxygen probes, one mounted nearthe printing station and another located near the UV station. Control ofoxygen was achieved by controlling a flow of separate streams of air andnitrogen that were mixed prior to entry into the processing enclosure.

Results

Cross-sections were made from hydrated samples printed on the glassmicroscope slides by cutting through the middle of the sample with twostacked surgical blades number 23. The 400 micron wide cut was thenplaced on the side in a petri-dish with 0.9% saline solution, allowed toequilibrate for an hour and the shape was monitored with a microscope.

Non-uniformity or stresses can then be seen as deviation from theintended shape, which in this case is flat.

Non-uniformity or stresses will adversely affect the optical propertiesof the material.

The appearance and tackiness of the non-hydrated sample (after curing at365 nm) were evaluated by visual inspection and by touch, respectively.

The light transmittance value for the hydrated hydrogel sample (10 mm×10mm) prepared as described above as well as that of a commercial ACUVUE 2contact lens as a reference (transmittance of 96.83%) was calculated asthe mean between 380 nm and 780 nm. See the table below.

The center thickness of the hydrated samples was measured optically withthe microscope on cross-sections.

Evaluation of Hydrated Hydrogel Samples PM Equiv. O₂ vol·% Atmosphere O₂vol·% Cross-section of hydrated lens Non-hydrated surface Hydrated LensAppearance; % Transmittance Center thickness µm PM-1A. 1.6% x-link 1<0.5% 0.1

Not tacky Clear 94.98% 166 2 <0.5% 1.0

Slightly tacky Clear 95.76% 153 3 <0.5% 2.1

Tacky Hazy 91.51% 172 4 <0.5% 5.3

Very tacky Hazy 80.09% 166 PM Equiv. O₂ vol·% Atmosphere O₂ vol·%Cross-section of hydrated lens Non-hydrated surface Hydrated LensAppearance; % Transmittance Center thickness µm PM-1B. 1.6% x-link 1 2%0.1

Not tacky Clear 96.37% 213 2 2% 1.0

Tacky Hazy n.d. 240 3 2% 2.0

Tacky Hazy n.d. 249 4 2% 5.0 x-section not possible Liquid on top Hazyn.d. PM Equiv. O₂ vol·% Atmosphere O₂ vol·% Cross-section of hydratedlens Non-hydrated surface Hydrated Lens Appearance; % TransmittanceCenter thickness µm PM-1C. 1.6% x-link 1 5% 0.1

Not tacky Clear 93.90% 220 2 5% 1.0

Tacky slightly hazy n.d. 207 3 5% 2.0

Tacky Hazy n.d. 245 4 5% 5.0

Liquid on top Hazy n.d. 237 PM Equiv. O₂ vol·% Atmosphere O₂ vol·%Cross-section of hydrated lens Non-hydrated surface Hydrated LensAppearance; % Transmittance Center thickness µm PM-2. 1.2% x-link 1<0.5% 0.1

Not tacky Clear 93.93% 294 2 <0.5% 0.5

Not tacky v slight hazy 94.48% 233 3 <0.5% 1.0

Tacky Hazy 92.46% 229 ACUVUE2 — — — 96.83% n.d. “n.d.” indicate that nomeasurement was conducted.

The oxygen level in the processing atmosphere impacts the formedarticle. The light transmittance of the hydrated samples, which isimportant for the optical function, is quite high at the low levels ofoxygen in the processing atmosphere (0.1%, 0.5% and 1.0%) and comparableto a commercially available contact lens. At 2.0% oxygen in theprocessing atmosphere, there is a decrease in light transmittance and at5.0% oxygen, a considerable decrease in light transmittance results.Similarly, cross-sections of the hydrated samples show that the lowestlevel of deformation is obtained with the low levels of oxygen in theprocessing atmosphere.

The oxygen level in the polymerizable mixture has some effect on thelight transmission, but up to 5.0% oxygen can be acceptable if oxygen inthe processing atmosphere is low. The cross-sections of the hydratedsamples show the lowest level of deformation at 2.0% and 5.0% oxygen inthe polymerizable mixture in combination with the low level of oxygen inthe processing atmosphere.

A low level of deformation as seen on the cross-sectioned samplesindicates that the product is uniform and suitable for opticalapplications.

For samples made with polymerization mixtures PM-3A, PM-3B and PM-3C,observations were made based on touch after 6 layers were printed andpinned without curing.

The oxygen concentration in the atmosphere was maintained at <0.5volume-% and was measured by an oxygen probe mounted close to bothprinting and pinning stations. Control of the oxygen concentration wasachieved by a flowmeter connected to a nitrogen tank.

Results

-   PM-3A having <0.5% Oxygen: Slightly tacky but not stringy-   PM-3B having 2.0% Oxygen: Slightly tacky but not stringy-   PM-3C having 8.5% Oxygen: Tacky and stringy

Example Series B-Preparation of Hydrogel Surfaces on PMMA Domes

In this series, dome shaped samples of varying thickness of polymerizedHEMA were prepared and evaluated.

Preparation of Polymerizable Mixture

-   HEMA: 97.9-98.1%-   EGDMA: 1.2-1.4%-   Irgacure 651: 0.5%-   Irgacure 819: 0.2%

The polymerizable mixture was prepared as described in a previousexperiment that corresponded to an oxygen equilibrium concentration of<0.5 volume-% such as in preparation of PM-1A and PM-2.

3D Printing Conditions:

PMMA (poly(methyl methacrylate)) domes after Tween 80 treatment, weredegassed overnight, labeled D and E and then used as the substrates. Sixlayers were deposited in diameters ranging from 4 mm to 11 mm with UVpinning at 400 nm for 15 secs after printing each layer and a final curewas done for 120 secs at 365 nm.

Results

The measurements of the two PMMA domes on which the hydrogel surface wasprinted were made three times and the measurements include three values:flattest radius of curvature, steepest radius of curvature and principalaxis.

PMMA Dome D tilted up & right:

-   1. 8.09/8.06 @ 180-   2. 8.10/7.94 @ 120-   3. 8.12/7.95 @ 112-   Mean: 8.10/7.99

PMMA Dome E tilted up & very slightly left:

-   1. 8.16/7.97 @ 82-   2. 8.16/7.97 @ 97-   3. 16/7.96 @ 94-   Mean: 8.16/7.97

The results demonstrate the following:

-   i. Presence of a regular optical surface (this is a required feature    of the surface to be able to make measurements with the    auto-keratometer),-   ii. Highly repeatable measurements of both the flattest and steepest    radii: Dome D: Flat range 0.03 mm; Steep range 0.12 mm; Dome E: Flat    range 0.00 mm; Steep range 0.01 mm. The axis indicates the principal    direction and varies due to setting up the dome in front of the    instrument without any specific markings, hence this variation is of    no relevance.-   iii. Both domes exhibited a small amount of astigmatism. The    astigmatism was calculated based upon two assumed refractive indices    using the power equation described under Radii of Curvature    Measurements.

PMMA Dome D with Hydrogel Surface (n=1.49) Power 1=60.49D, Power2=61.32D; Astigmatism=0.83D; (n=1.42) Power 1=51.85D; Power 2=52.57D;Astigmatism=0.72 D.

PMMA Dome F with Hydrogel Surface (n=1.49) Power 1=60.05D; Power2=61.48D; Astigmatism=1.43D; (n=1.42) Power 1=51.47D; Power 2=52.69D;Astigmarism=1.22D.

The front surfaces of the PMMA Domes printed with hydrogel surfacesabove correspond to the front surfaces of equivalent front surface toriccontact lenses, with Dome D equivalent to a 0.75D toric contact lens andDome E equivalent to a 1.25D toric contact lens.

Example Series C—Preparation of Embedded Inserts Preparation ofPolymerizable Mixture

Same as in Example series B. The polymerizable mixture was prepared asdescribed in a previous experiment that corresponded to an oxygenequilibrium concentration of <0.5 volume-% such as in preparation ofPM-1A and PM-2.

3D Printing Conditions

The oxygen concentration in the atmosphere was maintained at <0.5volume-% and was measured by two oxygen probes, one mounted near theprinting station and another located near the UV station. Control of theoxygen concentration was achieved by a flowmeter connected to a nitrogentank.

Degassed polypropylene spheres treated with Tween 80 were used assubstrates. Six layers were deposited in diameters ranging from 4 mm to11 mm with UV pinning at 400 nm for 15 secs after printing each layer. Ablue tinted PMMA insert (6 mm diameter and 50 microns thick) after Tween80 treatment, was degassed overnight, was placed on the pinned layersand two additional layers were deposited in 11 mm diameter with UVpinning at 400 nm for 15 secs after pinning each layer. A final cure wasdone for 120 secs at 365 nm.

Result

The blue tinted PMMA insert can be clearly observed and was found to betotally embedded within the hydrogel device. In addition, this methodcan be used to manufacture soft contact lenses with rigid inserts tomask astigmatism.

Example Series D----Preparation of Embedded Reservoirs or DepotsPreparation of Polymerizable Mixture

Same as in preparation of PM-2. The polymerizable mixture was preparedas described in a previous experiment that corresponded to an oxygenequilibrium concentration of <0.5 volume-% such as in preparation ofPM-1A and PM-2.

3D Printing Conditions

The oxygen concentration in the atmosphere was maintained at <0.5volume-% and was measured by two oxygen probes, one mounted near theprinting station and another located near the UV station. Control of theoxygen concentration was achieved by a flowmeter connected to a nitrogentank

Tween 80 treated glass hemispheres measuring 13 mm in diameter were usedas substrates. 15 layers were deposited with a diameter of 9.5 mms withUV pinning at 400 nm for 15 secs after printing each layer. A smallpiece of a plastic micropipette packed with food coloring crystals wasthen placed on the pinned 15 layers. Three additional layers with adiameter of 9.5 mms were deposited with UV pinning at 400 nm for 15 secsafter printing each layer. A few additional drops of the polymerizablemixture were deposited to ensure complete encapsulation of themicropipette piece and the assembly was cured for 120 secs at 365 nm.

Result

The plastic micropipette containing food coloring crystals can beclearly observed and was totally embedded within the hydrogel device.This method demonstrates the embedding of functional additive releasingreservoirs or depots within ophthalmic devices such as contact lenses.Subsequent hydration of the assembly in water showed the hydrating waterwas tinted and the absence of the food coloring crystals in themicropipette piece.

Example Series E-Preparation of Ophthalmic Devices With AsymmetricDesigns Preparation of Polymerizable Mixture

Same as in preparation of PM-2. The polymerizable mixture was preparedas described in a previous experiment that corresponded to an oxygenequilibrium concentration of <0.5 volume-% such as in preparation ofPM-1A and PM-2.

3D Printing Conditions:

The oxygen concentration in the atmosphere was maintained at <0.5volume-% and was measured by two oxygen probes, one mounted near theprinting station and another located near the UV station. Control of theoxygen concentration was achieved by a flowmeter connected to a nitrogentank.

Tween 80 treated glass hemispheres measuring 13 mm in diameter were usedas substrates. Ten layers with an asymmetrical design (Atheneum OpticalSciences Logo) measuring about 6 mm by 4 mm were deposited on thesubstrate with UV pinning at 400 nm for 15 secs after printing eachlayer. Then 17 layers were deposited with UV pinning at 400 nm for 15secs after printing each layer. The assembly was then cured for 120 secsat 365 nm.

Result

The asymmetrical design of the logo can be clearly observed within thehydrogel device before and after hydration in saline solution. Thismethod demonstrates the viability of incorporating asymmetric structuresto correct asymmetric refractive errors in ophthalmic devices such ascontact lenses.

Example Series F----- Preparation of Samples With Image Quality Opticsand Refractive Corrections Preparation of Polymerizable Mixture

-   HEMA: 95.4%-   MAA: 2.5%-   EGDMA: 1.2%-   TMPTMA: 0.1%-   Irgacure 819: 0.3%-   Irgacure 651: 0.5%

The polymerization mixture was prepared as described in a previousexperiment that corresponded to an oxygen equilibrium concentration of<0.5 volume-% similar to the preparation of PM-1A and PM-2.

3D Printing Conditions

The oxygen concentration in the atmosphere was maintained at <0.5volume-% and was measured by an oxygen probe mounted close to bothprinting and pinning stations. Control of the oxygen concentration wasachieved by flowmeters connected to a nitrogen tank. The Samba printhead resolution was set at 1200 dpi.

10.0 mm diameter circular designs were printed to generate the samples.Belt speed was set at 10.0 feet per minute. UV pinning or gelationoccurred after 10 sec exposure to the 400 nm UV lamp. Curing was donefor 120 sec by exposure to the 365 nm UV lamp. With printedprescriptions, foundation layers were first printed, pinned and cured;thereafter each prescription layer was pinned and then cured for 120secs after which a top or final coat was printed, pinned and cured.Substrates used for preparing the samples were glass microscope slidestreated with Tween 80 as described in Example series A. Power indiopters (D) was measured with a Topcon CL-200 lensometer. Dry power wasmeasured on the printed sample inclusive of the glass slide substratewhile the wet power was measured after releasing the sample from thehydrating solution (heated distilled water containing Tween 80 asdescribed earlier) and then equilibrating in saline solution for morethan 20 hours. The diameter of the hydrated samples was measured to be13.9±0.1 mm.

The results are shown in the Table below:

SAMPLE TARGET/ DESIGN POWER (D) FOUNDATION LAYERS (NUMBER) PRESCRIPTIONLAYERS (NUMBER) MEASURED DRY POWER (D) MEASURED WET POWER (D) 1 - 5 -0.00 to 0.25 0.00 to 0.25 2 - 10 - 0.00 to 0.25 0.00 to 0.25 3 +1.00 103 0.75 ± 0.00 0.75 ± 0.25 4 +3.00 10 3 3.00 ± 0.25 2.75 to 3.00

Results

The dry and wet power results shown in the table above indicate thatthree-dimensional deposition printing can produce optical devices withimage quality optics such as ophthalmic lenses to correct refractiveerrors.

General Remarks

Although the present description and claims occasionally refer to amixture (such as a polymerizable mixture), an initiator, otheradditives, it is within the scope of this invention that the materialsand compositions defined herein may comprise one, two, or more types ofindividual constituents. In such embodiments, a total amount of arespective constituent should correspond to an amount defined above forthe individual constituent.

The (s) in the expressions: mixture(s), initiator(s), etc. indicatesthat one, two, or more types of the individual constituents may bepresent. On the other hand, when the expression one is used, only one(1) of the respective constituent is present.

It should be understood that the expression % means the percentage ofthe respective component by weight, unless otherwise noted.

CONCLUSION

A number of embodiments of the present disclosure have been described.While this specification contains many specific implementation details,there should not be construed as limitations on the scope of anydisclosures or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments of the present disclosure.

Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented incombination in multiple embodiments separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous.

Moreover, separation of various system components in the embodimentsdescribed above should not be understood as requiring such separation inall embodiments, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlehardware and/or software product or packaged into multiple products.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order show, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous. Nevertheless, it will be understood thatvarious modifications may be made without departing from the spirit andscope of the claimed disclosure.

What is claimed is:
 1. A method of forming an ophthalmic lens viaadditive manufacturing, the method comprising the steps of: a.positioning a substrate at first position relative to an additivemanufacturing print head; b. emitting a first pattern of depositeddroplets of polymerizable mixture from a print head, the first patternof deposited droplets of polymerizable mixture corresponding with afirst portion of a grayscale image; c. receiving the deposited dropletsof polymerizable mixture on a receiving surface, the receiving surfacecomprising one or both of: the substrate, and previously emitteddroplets of polymerizable mixture; d. repositioning the substrate to anext position relative to the print head; e. emitting a next pattern ofdeposited droplets of polymerizable mixture from the print headcorresponding with a next portion of the grayscale image; f. repeatingsteps a. through e. multiple times during a pass of the print headrelative to the substrate; g. exposing the deposited droplets ofpolymerizable mixture on the receiving surface to a pinning processcausing partial polymerization of the deposited droplets ofpolymerizable mixture; h. repeating step f. for a next pass of the printhead relative to the substrate; i. following each pass included in steph., allowing gravity to act on at least some of the deposited dropletsof polymerizable mixture to smooth the surface of polymerizable mixture;j. following each pass included in step h., integrating at least some ofthe droplets of polymerizable mixture deposited during a current passwith polymerizable mixture previously deposited onto the receivingsurface to form a combined volume of polymerizable mixture on thesubstrate; k. following each step j., pinning the deposited droplets ofpolymerizable mixture on the receiving surface via the partialpolymerization of the deposited droplets of polymerizable mixture; andl. curing the combined volume of polymerizable mixture on the substrate.2. The method of claim 1, additionally comprising the step of containingthe substrate and the droplets of polymerizable mixture in a controlledatmosphere with an oxygen concentration of at the most 5.0 volume-%. 3.The method of claim 2 comprising the step of bringing an oxygenequilibrium concentration of die combined volume of polymerizablemixture on the substrate to at most 8.0 volume-%.
 4. The method of claim3 additionally comprising the step of bringing an oxygen concentrationin the substrate into equilibrium with an oxygen concentration in thecontrolled atmosphere.
 5. The method of claim 4 wherein at least one ofthe steps of: emitting a first pattern of deposited droplets ofpolymerizable mixture from a print head, and emitting a next pattern ofdeposited droplets of polymerizable mixture from a print head, comprisesemitting an amount of deposition of polymerizable mixture at a givenlocation that corresponds with data values associated with pixelsincluded in a grayscale image.
 6. The method of claim 5 wherein arelatively larger digital value corresponds with a darker area of thegrayscale image than a relatively smaller digital value correspondingwith a lighter area of the grayscale image.
 7. The method of claim 1,wherein the pinning process comprises the step of exposing the depositeddroplets of polymerizable mixture to a first wavelength of actinicradiation for a limited amount of time sufficient to cause gelation ofthe deposited droplets of polymerizable mixture and not cause curing ofthe deposited droplets of polymerizable mixture.
 8. The method of claim1, wherein the step of curing the combined volume of polymerizablemixture comprises the step of exposing the combined volume ofpolymerizable mixture on the substrate to a second wavelength of actinicradiation for a sufficient time and of sufficient intensity to causepolymerization of the deposited droplets of polymerizable mixture. 9.The method of claim 1 wherein the step of allowing gravity to act on atleast some of the deposited droplets of polymerizable mixture to smooththe surface of polymerizable mixture comprises at least partiallyfilling interstitial spaces between the deposited droplets ofpolymerizable mixture.
 10. The method of claim 9 additionally comprisingthe step of bringing an oxygen concentration in the substrate intoequilibrium with an oxygen concentration in a controlled atmospherecontaining the substrate and the deposited droplets of polymerizablemixture.
 11. A method of forming an ophthalmic lens via additivemanufacturing, the method comprising the steps of: a. positioning asubstrate at a first position relative to an additive manufacturingprint head; b. emitting a first pattern of deposited droplets ofpolymerizable mixture from the additive manufacturing print head, thefirst pattern of deposited droplets of polymerizable mixturecorresponding with a first portion of an energy transmissibilitypattern; c. receiving the deposited droplets of polymerizable mixture ona receiving surface; d. positioning the substrate at a next position(current position plus N) relative to the print head; e. emitting a nextpattern of deposited droplets of polymerizable mixture correspondingwith a next portion of the energy transmissibility pattern; f. allowingphysical forces to smooth a surface of droplets of polymerizable mixturedeposited during a current pass; g. integrating at least some of thedroplets of polymerizable mixture deposited during a current pass withpolymerizable mixture previously deposited onto the receiving surface,to form a combined volume of polymerizable mixture on the substrate; h.exposing the deposited droplets of polymerizable mixture on thereceiving surface to a pinning process causing partial polymerization ofthe deposited droplets of polymerizable mixture; i. repeating steps d.through h. for multiple passes of the print head relative to thesubstrate; and j. curing the combined volume of polymerizable mixture onthe substrate to produce the formed ophthalmic lens.
 12. The method ofclaim 11, wherein the step of receiving the deposited droplets ofpolymerizable mixture on a receiving surface comprises receiving thedeposited droplets one or more of: the substrate; previously emitteddroplets of polymerizable mixture; and an insert.
 13. The method ofclaim 12 additionally comprising repeating steps d. through g. multipletimes during a pass of the print head relative to the substrate.
 14. Themethod of claim 12 additionally comprising the step of releasing theformed ophthalmic lens from the substrate.
 15. The method of claim 12additionally comprising the step of allowing gravity to act on at leastsome of the deposited droplets of polymerizable mixture to at leastpartially fill interstitial spaces between the deposited droplets ofpolymerizable mixture.
 16. The method of claim 11, wherein the pinningprocess comprises the step of exposing the deposited droplets ofpolymerizable mixture to a first wavelength of actinic radiation for alimited amount of time sufficient to cause gelation of the depositeddroplets of polymerizable mixture, and not cause curing of the depositeddroplets of polymerizable mixture.
 17. The method of claim 16, whereinthe step of curing the combined volume of polymerizable mixture on thesubstrate comprises exposing the combined volume of polymerizablemixture on the substrate to a second wavelength of actinic radiation fora sufficient time, and of sufficient intensity to cause polymerizationof the combined volume of polymerizable mixture on the substrate. 18.The method of claim 16 additionally comprising repeating steps d.through g. for between 5 and 20 passes of the substrate relative to theprinthead.
 19. The method of claim 11 additionally comprising the stepof containing the substrate and polymerizable mixture in a controlledatmosphere with an oxygen concentration comprising at most 2.0 volume-%.20. The method of claim 19 additionally comprising the step of bringingan oxygen concentration in the substrate into equilibrium with an oxygenconcentration in the controlled atmosphere.
 21. The method of claim 20wherein the substrate comprises at least one of: glass, a polyolefin andpolystyrene.
 22. The method of claim 19 additionally comprising the stepof generating a control command for the additive manufacturing printhead based upon the energy transmissibility pattern.
 23. The method ofclaim 22 additionally comprising the step of dithering the energytransmissibility pattern prior to generation of the control command. 24.The method of claim 23 wherein the dithering comprises processesconsistent with one or more of: Floyd-Steinberg, Burkes, Sierra, Two RowSierra, Jarvis, Stevenson, and Arce, and results in a smootherdisposition of droplets of polymerizable mixture.